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• Confusion related to sigwait in multiprocess system

  - by user34790

  I am having difficulty in understanding IPC in multiprocess system. I have this system where there are three child processes that send two types of signals to their process group. There are four types of signal handling processes responsible for a particular type of signal. There is this monitoring process which waits for both the signals and then processes accordingly. When I run this program for a while, the monitoring process doesn't seem to pick up the signal as well as the signal handling process. I could see in the log that the signal is only being generated but not handled at all. My code is given below #include <cstdlib> #include <iostream> #include <iomanip> #include <unistd.h> #include <sys/types.h> #include <sys/wait.h> #include <sys/time.h> #include <signal.h> #include <unistd.h> #include <fcntl.h> #include <cstdio> #include <stdlib.h> #include <stdio.h> #include <pthread.h> using namespace std; double timestamp() { struct timeval tp; gettimeofday(&tp, NULL); return (double)tp.tv_sec + tp.tv_usec / 1000000.; } double getinterval() { srand(time(NULL)); int r = rand()%10 + 1; double s = (double)r/100; } int count; int count_1; int count_2; double time_1[10]; double time_2[10]; pid_t senders[1]; pid_t handlers[4]; pid_t reporter; void catcher(int sig) { printf("Signal catcher called for %d",sig); } int main(int argc, char *argv[]) { void signal_catcher_int(int); pid_t pid,w; int status; if(signal(SIGUSR1, SIG_IGN) == SIG_ERR) { perror("1"); return 1; } if(signal(SIGUSR2 ,SIG_IGN) == SIG_ERR) { perror("2"); return 2; } if(signal(SIGINT,signal_catcher_int) == SIG_ERR) { perror("3"); return 2; } //Registering the signal handler for(int i=0; i<4; i++) { if((pid = fork()) == 0) { cout << i << endl; //struct sigaction sigact; sigset_t sigset; int sig; int result = 0; sigemptyset(&sigset); if(i%2 == 0) { if(signal(SIGUSR2, SIG_IGN) == SIG_ERR) { perror("2"); return 2; } sigaddset(&sigset, SIGUSR1); sigprocmask(SIG_BLOCK, &sigset, NULL); } else { if(signal(SIGUSR1, SIG_IGN) == SIG_ERR) { perror("2"); return 2; } sigaddset(&sigset, SIGUSR2); sigprocmask(SIG_BLOCK, &sigset, NULL); } while(true) { int result = sigwait(&sigset, &sig); if(result == 0) { cout << "The caught signal is " << sig << endl; } } exit(0); } else { cout << "Registerd the handler " << pid << endl; handlers[i] = pid; } } //Registering the monitoring process if((pid = fork()) == 0) { sigset_t sigset; int sig; int result = 0; sigemptyset(&sigset); sigaddset(&sigset, SIGUSR1); sigaddset(&sigset, SIGUSR2); sigprocmask(SIG_BLOCK, &sigset, NULL); while(true) { int result = sigwait(&sigset, &sig); if(result == 0) { cout << "The monitored signal is " << sig << endl; } else { cout << "error" << endl; } } } else { reporter = pid; } sleep(3); //Registering the signal generator for(int i=0; i<1; i++) { if((pid = fork()) == 0) { if(signal(SIGUSR1, SIG_IGN) == SIG_ERR) { perror("1"); return 1; } if(signal(SIGUSR2, SIG_IGN) == SIG_ERR) { perror("2"); return 2; } srand(time(0)); while(true) { volatile int signal_id = rand()%2 + 1; cout << "Generating the signal " << signal_id << endl; if(signal_id == 1) { killpg(getpgid(getpid()), SIGUSR1); } else { killpg(getpgid(getpid()), SIGUSR2); } int r = rand()%10 + 1; double s = (double)r/100; sleep(s); } exit(0); } else { cout << "Registered the sender " << pid << endl; senders[i] = pid; } } while(w = wait(&status)) { cout << "Wait on PID " << w << endl; } } void signal_catcher_int(int the_sig) { //cout << "Handling the Ctrl C signal " << endl; for(int i=0; i<1; i++) { kill(senders[i],SIGKILL); } for(int i=0; i<4; i++) { kill(handlers[i],SIGKILL); } kill(reporter,SIGKILL); exit(3); } Any suggestions? Here is a sample of the output as well In the beginning Registerd the handler 9544 Registerd the handler 9545 1 Registerd the handler 9546 Registerd the handler 9547 2 3 0 Registered the sender 9550 Generating the signal 1 The caught signal is 10 The monitored signal is 10 The caught signal is 10 Generating the signal 1 The caught signal is 10 The monitored signal is 10 The caught signal is 10 Generating the signal 1 The caught signal is 10 The monitored signal is 10 The caught signal is 10 Generating the signal 1 The caught signal is 10 The monitored signal is 10 The caught signal is 10 Generating the signal 2 The caught signal is 12 The caught signal is 12 The monitored signal is 12 Generating the signal 2 Generating the signal 2 The caught signal is 12 The caught signal is 12 Generating the signal 1 The caught signal is 12 The monitored signal is 10 The monitored signal is 12 Generating the signal 1 Generating the signal 2 The caught signal is 12 Generating the signal 1 Generating the signal 2 10 The monitored signal is 10 The caught signal is 12 Generating the signal 1 The caught signal is 12 The monitored signal is GenThe caught signal is TheThe caught signal is 10 Generating the signal 2 Later on The monitored signal is GenThe monitored signal is 10 Generating the signal 1 Generating the signal 2 The caught signal is 10 The caught signal is 10 The caught signal is 10 The caught signal is 12 Generating the signal 1 Generating the signal 2 Generating the signal 1 Generating the signal 1 Generating the signal 2 Generating the signal 2 Generating the signal 2 Generating the signal 2 Generating the signal 2 Generating the signal 1 The caught signal is 12 The caught signal is 10 The caught signal is 10 Generating the signal 2 Generating the signal 1 Generating the signal 1 Generating the signal 2 Generating the signal 1 Generating the signal 2 Generating the signal 2 Generating the signal 2 Generating the signal 1 Generating the signal 2 Generating the signal 1 Generating the signal 2 Generating the signal 2 The caught signal is 10 Generating the signal 2 Generating the signal 1 Generating the signal 1 As you can see initially, the signal was generated and handled both by my signal handlers and monitoring processes. But later on the signal was generated a lot, but it was not quite processes in the same magnitude as before. Further I could see very less signal processing by the monitoring process Can anyone please provide some insights. What's going on?

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• Of transactions and Mongo

  - by Nuri Halperin

  Originally posted on: http://geekswithblogs.net/nuri/archive/2014/05/20/of-transactions-and-mongo-again.aspxWhat's the first thing you hear about NoSQL databases? That they lose your data? That there's no transactions? No joins? No hope for "real" applications? Well, you *should* be wondering whether a certain of database is the right one for your job. But if you do so, you should be wondering that about "traditional" databases as well! In the spirit of exploration let's take a look at a common challenge: You are a bank. You have customers with accounts. Customer A wants to pay B. You want to allow that only if A can cover the amount being transferred. Let's looks at the problem without any context of any database engine in mind. What would you do? How would you ensure that the amount transfer is done "properly"? Would you prevent a "transaction" from taking place unless A can cover the amount? There are several options: Prevent any change to A's account while the transfer is taking place. That boils down to locking. Apply the change, and allow A's balance to go below zero. Charge person A some interest on the negative balance. Not friendly, but certainly a choice. Don't do either. Options 1 and 2 are difficult to attain in the NoSQL world. Mongo won't save you headaches here either. Option 3 looks a bit harsh. But here's where this can go: ledger. See, and account doesn't need to be represented by a single row in a table of all accounts with only the current balance on it. More often than not, accounting systems use ledgers. And entries in ledgers - as it turns out – don't actually get updated. Once a ledger entry is written, it is not removed or altered. A transaction is represented by an entry in the ledger stating and amount withdrawn from A's account and an entry in the ledger stating an addition of said amount to B's account. For sake of space-saving, that entry in the ledger can happen using one entry. Think {Timestamp, FromAccountId, ToAccountId, Amount}. The implication of the original question – "how do you enforce non-negative balance rule" then boils down to: Insert entry in ledger Run validation of recent entries Insert reverse entry to roll back transaction if validation failed. What is validation? Sum up the transactions that A's account has (all deposits and debits), and ensure the balance is positive. For sake of efficiency, one can roll up transactions and "close the book" on transactions with a pseudo entry stating balance as of midnight or something. This lets you avoid doing math on the fly on too many transactions. You simply run from the latest "approved balance" marker to date. But that's an optimization, and premature optimizations are the root of (some? most?) evil.. Back to some nagging questions though: "But mongo is only eventually consistent!" Well, yes, kind of. It's not actually true that Mongo has not transactions. It would be more descriptive to say that Mongo's transaction scope is a single document in a single collection. A write to a Mongo document happens completely or not at all. So although it is true that you can't update more than one documents "at the same time" under a "transaction" umbrella as an atomic update, it is NOT true that there' is no isolation. So a competition between two concurrent updates is completely coherent and the writes will be serialized. They will not scribble on the same document at the same time. In our case - in choosing a ledger approach - we're not even trying to "update" a document, we're simply adding a document to a collection. So there goes the "no transaction" issue. Now let's turn our attention to consistency. What you should know about mongo is that at any given moment, only on member of a replica set is writable. This means that the writable instance in a set of replicated instances always has "the truth". There could be a replication lag such that a reader going to one of the replicas still sees "old" state of a collection or document. But in our ledger case, things fall nicely into place: Run your validation against the writable instance. It is guaranteed to have a ledger either with (after) or without (before) the ledger entry got written. No funky states. Again, the ledger writing *adds* a document, so there's no inconsistent document state to be had either way. Next, we might worry about data loss. Here, mongo offers several write-concerns. Write-concern in Mongo is a mode that marshals how uptight you want the db engine to be about actually persisting a document write to disk before it reports to the application that it is "done". The most volatile, is to say you don't care. In that case, mongo would just accept your write command and say back "thanks" with no guarantee of persistence. If the server loses power at the wrong moment, it may have said "ok" but actually no written the data to disk. That's kind of bad. Don't do that with data you care about. It may be good for votes on a pole regarding how cute a furry animal is, but not so good for business. There are several other write-concerns varying from flushing the write to the disk of the writable instance, flushing to disk on several members of the replica set, a majority of the replica set or all of the members of a replica set. The former choice is the quickest, as no network coordination is required besides the main writable instance. The others impose extra network and time cost. Depending on your tolerance for latency and read-lag, you will face a choice of what works for you. It's really important to understand that no data loss occurs once a document is flushed to an instance. The record is on disk at that point. From that point on, backup strategies and disaster recovery are your worry, not loss of power to the writable machine. This scenario is not different from a relational database at that point. Where does this leave us? Oh, yes. Eventual consistency. By now, we ensured that the "source of truth" instance has the correct data, persisted and coherent. But because of lag, the app may have gone to the writable instance, performed the update and then gone to a replica and looked at the ledger there before the transaction replicated. Here are 2 options to deal with this. Similar to write concerns, mongo support read preferences. An app may choose to read only from the writable instance. This is not an awesome choice to make for every ready, because it just burdens the one instance, and doesn't make use of the other read-only servers. But this choice can be made on a query by query basis. So for the app that our person A is using, we can have person A issue the transfer command to B, and then if that same app is going to immediately as "are we there yet?" we'll query that same writable instance. But B and anyone else in the world can just chill and read from the read-only instance. They have no basis to expect that the ledger has just been written to. So as far as they know, the transaction hasn't happened until they see it appear later. We can further relax the demand by creating application UI that reacts to a write command with "thank you, we will post it shortly" instead of "thank you, we just did everything and here's the new balance". This is a very powerful thing. UI design for highly scalable systems can't insist that the all databases be locked just to paint an "all done" on screen. People understand. They were trained by many online businesses already that your placing of an order does not mean that your product is already outside your door waiting (yes, I know, large retailers are working on it... but were' not there yet). The second thing we can do, is add some artificial delay to a transaction's visibility on the ledger. The way that works is simply adding some logic such that the query against the ledger never nets a transaction for customers newer than say 15 minutes and who's validation flag is not set. This buys us time 2 ways: Replication can catch up to all instances by then, and validation rules can run and determine if this transaction should be "negated" with a compensating transaction. In case we do need to "roll back" the transaction, the backend system can place the timestamp of the compensating transaction at the exact same time or 1ms after the original one. Effectively, once A or B visits their ledger, both transactions would be visible and the overall balance "as of now" would reflect no change.  The 2 transactions (attempted/ reverted) would be visible , since we do actually account for the attempt. Hold on a second. There's a hole in the story: what if several transfers from A to some accounts are registered, and 2 independent validators attempt to compute the balance concurrently? Is there a chance that both would conclude non-sufficient-funds even though rolling back transaction 100 would free up enough for transaction 117 (some random later transaction)? Yes. there is that chance. But the integrity of the business rule is not compromised, since the prime rule is don't dispense money you don't have. To minimize or eliminate this scenario, we can also assign a single validation process per origin account. This may seem non-scalable, but it can easily be done as a "sharded" distribution. Say we have 11 validation threads (or processing nodes etc.). We divide the account number space such that each validator is exclusively responsible for a certain range of account numbers. Sounds cunningly similar to Mongo's sharding strategy, doesn't it? Each validator then works in isolation. More capacity needed? Chop the account space into more chunks. So where  are we now with the nagging questions? "No joins": Huh? What are those for? "No transactions": You mean no cross-collection and no cross-document transactions? Granted - but don't always need them either. "No hope for real applications": well... There are more issues and edge cases to slog through, I'm sure. But hopefully this gives you some ideas of how to solve common problems without distributed locking and relational databases. But then again, you can choose relational databases if they suit your problem.

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• How to install SpatiaLite 3 on 12.04

  - by Terra

  1) sudo apt-get install libsqlite3-dev libgeos-dev 2) libspatialite-3.0.0-stable$ ./configure Result: configure: error: cannot find proj_api.h, bailing out checking for a BSD-compatible install... /usr/bin/install -c checking whether build environment is sane... yes checking for a thread-safe mkdir -p... /bin/mkdir -p checking for gawk... no checking for mawk... mawk checking whether make sets $(MAKE)... yes checking whether to enable maintainer-specific portions of Makefiles... no checking for style of include used by make... GNU checking for gcc... gcc checking whether the C compiler works... yes checking for C compiler default output file name... a.out checking for suffix of executables... checking whether we are cross compiling... no checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ISO C89... none needed checking dependency style of gcc... gcc3 checking how to run the C preprocessor... gcc -E checking for grep that handles long lines and -e... /bin/grep checking for egrep... /bin/grep -E checking for ANSI C header files... yes checking for sys/types.h... yes checking for sys/stat.h... yes checking for stdlib.h... yes checking for string.h... yes checking for memory.h... yes checking for strings.h... yes checking for inttypes.h... yes checking for stdint.h... yes checking for unistd.h... yes checking for stdlib.h... (cached) yes checking stdio.h usability... yes checking stdio.h presence... yes checking for stdio.h... yes checking for string.h... (cached) yes checking for memory.h... (cached) yes checking math.h usability... yes checking math.h presence... yes checking for math.h... yes checking float.h usability... yes checking float.h presence... yes checking for float.h... yes checking fcntl.h usability... yes checking fcntl.h presence... yes checking for fcntl.h... yes checking for inttypes.h... (cached) yes checking stddef.h usability... yes checking stddef.h presence... yes checking for stddef.h... yes checking for stdint.h... (cached) yes checking sys/time.h usability... yes checking sys/time.h presence... yes checking for sys/time.h... yes checking for unistd.h... (cached) yes checking sqlite3.h usability... yes checking sqlite3.h presence... yes checking for sqlite3.h... yes checking sqlite3ext.h usability... yes checking sqlite3ext.h presence... yes checking for sqlite3ext.h... yes checking for g++... no checking for c++... no checking for gpp... no checking for aCC... no checking for CC... no checking for cxx... no checking for cc++... no checking for cl.exe... no checking for FCC... no checking for KCC... no checking for RCC... no checking for xlC_r... no checking for xlC... no checking whether we are using the GNU C++ compiler... no checking whether g++ accepts -g... no checking dependency style of g++... none checking for gcc... (cached) gcc checking whether we are using the GNU C compiler... (cached) yes checking whether gcc accepts -g... (cached) yes checking for gcc option to accept ISO C89... (cached) none needed checking dependency style of gcc... (cached) gcc3 checking how to run the C preprocessor... gcc -E checking whether ln -s works... yes checking whether make sets $(MAKE)... (cached) yes checking build system type... i686-pc-linux-gnu checking host system type... i686-pc-linux-gnu checking how to print strings... printf checking for a sed that does not truncate output... /bin/sed checking for fgrep... /bin/grep -F checking for ld used by gcc... /usr/bin/ld checking if the linker (/usr/bin/ld) is GNU ld... yes checking for BSD- or MS-compatible name lister (nm)... /usr/bin/nm -B checking the name lister (/usr/bin/nm -B) interface... BSD nm checking the maximum length of command line arguments... 1572864 checking whether the shell understands some XSI constructs... yes checking whether the shell understands "+="... yes checking how to convert i686-pc-linux-gnu file names to i686-pc-linux-gnu format... func_convert_file_noop checking how to convert i686-pc-linux-gnu file names to toolchain format... func_convert_file_noop checking for /usr/bin/ld option to reload object files... -r checking for objdump... objdump checking how to recognize dependent libraries... pass_all checking for dlltool... dlltool checking how to associate runtime and link libraries... printf %s\n checking for ar... ar checking for archiver @FILE support... @ checking for strip... strip checking for ranlib... ranlib checking command to parse /usr/bin/nm -B output from gcc object... ok checking for sysroot... no checking for mt... mt checking if mt is a manifest tool... no checking for dlfcn.h... yes checking for objdir... .libs checking if gcc supports -fno-rtti -fno-exceptions... no checking for gcc option to produce PIC... -fPIC -DPIC checking if gcc PIC flag -fPIC -DPIC works... yes checking if gcc static flag -static works... yes checking if gcc supports -c -o file.o... yes checking if gcc supports -c -o file.o... (cached) yes checking whether the gcc linker (/usr/bin/ld) supports shared libraries... yes checking whether -lc should be explicitly linked in... no checking dynamic linker characteristics... GNU/Linux ld.so checking how to hardcode library paths into programs... immediate checking whether stripping libraries is possible... yes checking if libtool supports shared libraries... yes checking whether to build shared libraries... yes checking whether to build static libraries... yes checking for an ANSI C-conforming const... yes checking for off_t... yes checking for size_t... yes checking whether time.h and sys/time.h may both be included... yes checking whether struct tm is in sys/time.h or time.h... time.h checking for working volatile... yes checking whether lstat correctly handles trailing slash... yes checking whether lstat accepts an empty string... no checking whether lstat correctly handles trailing slash... (cached) yes checking for working memcmp... yes checking whether stat accepts an empty string... no checking for strftime... yes checking for memset... yes checking for sqrt... no checking for strcasecmp... yes checking for strerror... yes checking for strncasecmp... yes checking for strstr... yes checking for fdatasync... yes checking for ftruncate... yes checking for getcwd... yes checking for gettimeofday... yes checking for localtime_r... yes checking for memmove... yes checking for strerror... (cached) yes checking for sqlite3_prepare_v2 in -lsqlite3... yes checking for sqlite3_rtree_geometry_callback in -lsqlite3... yes checking proj_api.h usability... no checking proj_api.h presence... no checking for proj_api.h... no configure: error: cannot find proj_api.h, bailing out

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• CodePlex Daily Summary for Sunday, February 13, 2011

  CodePlex Daily Summary for Sunday, February 13, 2011Popular ReleasesTV4Home - The all-in-one TV solution!: 0.1.0.0 Preview: This is the beta preview release of the TV4Home software.Finestra Virtual Desktops: 1.2: Fixes a few minor issues with 1.1 including the broken per-desktop backgrounds Further improves the speed of switching desktops A few UI performance improvements Added donations linksNuGet: NuGet 1.1: NuGet is a free, open source developer focused package management system for the .NET platform intent on simplifying the process of incorporating third party libraries into a .NET application during development. This release is a Visual Studio 2010 extension and contains the the Package Manager Console and the Add Package Dialog. The URL to the package OData feed is: http://go.microsoft.com/fwlink/?LinkID=206669 To see the list of issues fixed in this release, visit this our issues listEnhSim: EnhSim 2.4.0: 2.4.0This release supports WoW patch 4.06 at level 85 To use this release, you must have the Microsoft Visual C++ 2010 Redistributable Package installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=A7B7A05E-6DE6-4D3A-A423-37BF0912DB84 To use the GUI you must have the .NET 4.0 Framework installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=9cfb2d51-5ff4-4491-b0e5-b386f32c0992 Changes since 2.3.0 - Upd...Sterling Isolated Storage Database with LINQ for Silverlight and Windows Phone 7: Sterling OODB v1.0: Note: use this changeset to download the source example that has been extended to show database generation, backup, and restore in the desktop example. Welcome to the Sterling 1.0 RTM. This version is not backwards-compatible with previous versions of Sterling. Sterling is also available via NuGet. This product has been used and tested in many applications and contains a full suite of unit tests. You can refer to the User's Guide for complete documentation, and use the unit tests as guide...PDF Rider: PDF Rider 0.5.1: Changes from the previous version * Use dynamic layout to better fit text in other languages * Includes French and Spanish localizations Prerequisites * Microsoft Windows Operating Systems (XP - Vista - 7) * Microsoft .NET Framework 3.5 runtime * A PDF rendering software (i.e. Adobe Reader) that can be opened inside Internet Explorer. Installation instructionsChoose one of the following methods: 1. Download and run the "pdfRider0.5.1-setup.exe" (reccomended) 2. Down...Snoop, the WPF Spy Utility: Snoop 2.6.1: This release is a bug fixing release. Most importantly, issues have been seen around WPF 4.0 applications not always showing up in the app chooser. Hopefully, they are fixed now. I thought this issue warranted a minor release since more and more people are going WPF 4.0 and I don't want anyone to have any problems. Dan Hanan also contributes again with several usability features. Thanks Dan! Happy Snooping! p.s. By request, I am also attaching a .zip file ... so that people can install it ...RIBA - Rich Internet Business Application for Silverlight: Preview of MVVM Framework Source + Tutorials: This is a first public release of the MVVM Framework which is part of the final RIBA application. The complete RIBA example LOB application has yet to be published. Further Documentation on the MVVM part can be found on the Blog, http://www.SilverlightBlog.Net and in the downloadable source ( mvvm/doc/ ). Please post all issues and suggestions in the issue tracker.SharePoint Learning Kit: 1.5: SharePoint Learning Kit 1.5 has the following new functionality: *Support for SharePoint 2010 *E-Learning Actions can be localised *Two New Document Library Edit Options *Automatically add the Assignment List Web Part to the Web Part Gallery *Various Bug Fixes for the Drop Box There are 2 downloads for this release SLK-1.5-2010.zip for SharePoint 2010 SLK-1.5-2007.zip for SharePoint 2007 (WSS3 & MOSS 2007)Facebook C# SDK: 5.0.3 (BETA): This is fourth BETA release of the version 5 branch of the Facebook C# SDK. Remember this is a BETA build. Some things may change or not work exactly as planned. We are absolutely looking for feedback on this release to help us improve the final 5.X.X release. For more information about this release see the following blog posts: Facebook C# SDK - Writing your first Facebook Application Facebook C# SDK v5 Beta Internals Facebook C# SDK V5.0.0 (BETA) Released We have spend time trying ...NodeXL: Network Overview, Discovery and Exploration for Excel: NodeXL Excel Template, version 1.0.1.161: The NodeXL Excel template displays a network graph using edge and vertex lists stored in an Excel 2007 or Excel 2010 workbook. What's NewThis release adds a new Twitter List network importer, makes some minor feature improvements, and fixes a few bugs. See the Complete NodeXL Release History for details. Installation StepsFollow these steps to install and use the template: Download the Zip file. Unzip it into any folder. Use WinZip or a similar program, or just right-click the Zip file...WCF Data Services Toolkit: WCF Data Services Toolkit: The source code and binary releases of the WCF Data Services Toolkit. For simplicity, the source code download doesn't include any of the MSTest files. If you want those, you can pull the code down via MercurialyoutubeFisher: youtubeFisher 3.0 [beta]: What's new: Video capturing improved Supports YouTube's new layout (january 2011) Internal refactoringNearforums - ASP.NET MVC forum engine: Nearforums v5.0: Version 5.0 of the ASP.NET MVC Forum Engine, containing the following improvements: .NET 4.0 as target framework using ASP.NET MVC 3. All views migrated to Razor for cleaner markup. Alternate template (Layout file) for mobile devices 4 Bug Fixes since Version 4.1 Visit the project Roadmap for more details. Webdeploy package sha1 checksum: 28785b7248052465ea0738a7775e8e8744d84c27fuv: 1.0 release, codename Chopper Joe: features: search/replace :o to open file :s to save file :q to quitASP.NET MVC Project Awesome, jQuery Ajax helpers (controls): 1.7: A rich set of helpers (controls) that you can use to build highly responsive and interactive Ajax-enabled Web applications. These helpers include Autocomplete, AjaxDropdown, Lookup, Confirm Dialog, Popup Form, Popup and Pager html generation optimized new features for the lookup (add additional search data ) live demo went aeroAutoLoL: AutoLoL v1.5.5: AutoChat now allows up to 6 items. Items with nr. 7-0 will be removed! News page url's are now opened in the default browser Added a context menu to the system tray icon (thanks to Alex Banagos) AutoChat now allows configuring the Chat Keys and the Modifier Key The recent files list now supports compact and full mode Fix: Swapped mouse buttons are now properly detected Fix: Sometimes the Play button was pressed while still greyed out Champion: Karma Note: You can also run the u...mojoPortal: 2.3.6.2: see release notes on mojoportal.com http://www.mojoportal.com/mojoportal-2362-released.aspx Note that we have separate deployment packages for .NET 3.5 and .NET 4.0 The deployment package downloads on this page are pre-compiled and ready for production deployment, they contain no C# source code. To download the source code see the Source Code Tab I recommend getting the latest source code using TortoiseHG, you can get the source code corresponding to this release here.Rawr: Rawr 4.0.19 Beta: Rawr is now web-based. The link to use Rawr4 is: http://elitistjerks.com/rawr.phpThis is the Cataclysm Beta Release. More details can be found at the following link http://rawr.codeplex.com/Thread/View.aspx?ThreadId=237262 As of the 4.0.16 release, you can now also begin using the new Downloadable WPF version of Rawr!This is a pre-alpha release of the WPF version, there are likely to be a lot of issues. If you have a problem, please follow the Posting Guidelines and put it into the Issue Trac...IronRuby: 1.1.2: IronRuby 1.1.2 is a servicing release that keeps on improving compatibility with Ruby 1.9.2 and includes IronRuby integration to Visual Studio 2010. We decided to drop 1.8.6 compatibility mode in all post-1.0 releases. We recommend using IronRuby 1.0 if you need 1.8.6 compatibility. In this release we fixed several major issues: - problems that blocked Gem installation in certain cases - regex syntax: the parser was replaced with a new one that is much more compatible with Ruby 1.9.2 - cras...New ProjectsAbstract | .NET DDD abstraction for infra-structure (Data, Blobs, Queues): In the last few years we have seen many tools abstract access to infra-structures. They are all very different - what makes it difficult for you to move from Azure or to Azure. Abstract makes migration easier by standardising access to these infra-structures.Apex APRS: Apex APRS is a new APRS client application that is unlike any other. Key Features: Online and offline-cached map viewing from multiple popular sources Fast, simple, intuitive & powerful user interface Customizable Notification System: Customizable Notification SystemDaniel Singleton for C++: An elegant solution for C++ singletons using dependency declaration to control lifetime. One object created during any execution, lazy-init, thread safety... nice and compact.Deduplicator: Deduplicator helps to organize your file system. Create one folder organized by choice containing unique files. To be used for photo's, mp3's or any other binary format. Deduplicator is released yet, user interface is limited and some hardcoding is still in placeDigitypon (ASP.NET MVC 3): Digitypon will be a new web application specialized to be used by those who want to set an e-newspaper or an e-magazine. The main difference among other CMSs is that Digitypon’s workflow is a virtualized way of how employees of printed matters (newspaperes, magazinews) work.EdgeJournalImporter: Import journal files written on the Entourage (Pocket) Edge into Microsoft OneNote 2007+FlatFileSerializer: Serialize and deserialize flat file records from and to self defined classes using Attributes.Google Chart Helper: Controls to insert Google Charts to your web application. No Javascript code to do. We do it for you !How to display records from MySQL 5.1 database in asp.net using VB.net or CSharp: How to display records from MySQl 5.1+ database in asp.net with vb.net or C# code.HTTP Filer: HTTP Filer is a utility that allow users to share files and documents over http protocol. This utility was designed especially for Windows Phone users to send files from computer to their phone easily without send emails with attachments or upload files to an internet server.ibamonitoring: Source code for the avian point-count data collection web site www.ibamonitoring.org.JoPack Ultra Light Packaging for large teams: JoPack is an opensource ultra light package management software – that is targeted for simplifying development with large teams sharing volatile assemblies across several solutions. Latest project source code can be found on project home site: http://code.google.com/p/jo-pack/ L-System Turtle Based Fractal Tool (L-Fractal Tool): A tool to help you play with L-System turtle graphic based fractal curves( http://en.wikipedia.org/wiki/L-system) This tool helps you look into some of the well known curves & lets you define new patterns & production rules to build your own. Have a fun-fractal day !mailer: mailer is a application to mail. It's developed in Python.NJamb: A C# DSL for more rigorous tests: NJamb is a C# syntax for tests and DDD specifications. It makes them more readable, faster to write, and more rigorous. Its Linq-style expressions can assert preconditions and postconditions. IntelliSense makes the syntax almost foolproof. And, it's designed to be extended.NUpdater: NUpdater makes it easier for .NET Framework developers to add auto-updating capability to their software. Putting together numerous patching capabilities, this library is an all-around updater. Developed in C# with CLS compliance (this library is fully compatible with Mono).Perihelia - The .NET & Silverlight Socket Project: Perihelia is an open-source socket framework. The framework includes (or will include) all the necessities you need to satisfy your networking needs. Windows and WPF applications are currently supported, and Silverlight applications will be supported soon.PLogger: PLogger is a light, fast configuration-less file appender logger build using a parallel pipeline architecture. It is much easier and faster to set up and use then Log4Net or the enterprise libraryQuasar: Quasar is a professional .Net utility library which adds sugar on .net framework.Sectors Game Engine: Sectors is a XNA-based 2.5D (Doom-like) game engine with console and scripting support for Windows.SharePoint 2010 Server-Side-Scanner WebPart - embDocumentInhalator: embDocumentInhalator makes it possible for SharePoint 2010 users to scan documents from scanners attached directly to the server. For developers it may help to see the relationship between the individual components required. SIAJUR: Projeto Web para controle de documentossvcutil2: svcutil2 generates Wcf client proxies from Wsdl2 documents.TemporalMemoryNetwork: TemporalMemoryNetwork is a research project exploring how dynamical systems can store and represent patterns that occur through time.WebDAV#: This project aims to implement WebDAV support for .NET, both for client software as well as software hosting their own WebDAV server. The project will start with the server portion. The project will be developed in C# 3.5 for .NET 3.5 and 4.0.

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• Inside the Concurrent Collections: ConcurrentDictionary

  - by Simon Cooper

  Using locks to implement a thread-safe collection is rather like using a sledgehammer - unsubtle, easy to understand, and tends to make any other tool redundant. Unlike the previous two collections I looked at, ConcurrentStack and ConcurrentQueue, ConcurrentDictionary uses locks quite heavily. However, it is careful to wield locks only where necessary to ensure that concurrency is maximised. This will, by necessity, be a higher-level look than my other posts in this series, as there is quite a lot of code and logic in ConcurrentDictionary. Therefore, I do recommend that you have ConcurrentDictionary open in a decompiler to have a look at all the details that I skip over. The problem with locks There's several things to bear in mind when using locks, as encapsulated by the lock keyword in C# and the System.Threading.Monitor class in .NET (if you're unsure as to what lock does in C#, I briefly covered it in my first post in the series): Locks block threads The most obvious problem is that threads waiting on a lock can't do any work at all. No preparatory work, no 'optimistic' work like in ConcurrentQueue and ConcurrentStack, nothing. It sits there, waiting to be unblocked. This is bad if you're trying to maximise concurrency. Locks are slow Whereas most of the methods on the Interlocked class can be compiled down to a single CPU instruction, ensuring atomicity at the hardware level, taking out a lock requires some heavy lifting by the CLR and the operating system. There's quite a bit of work required to take out a lock, block other threads, and wake them up again. If locks are used heavily, this impacts performance. Deadlocks When using locks there's always the possibility of a deadlock - two threads, each holding a lock, each trying to aquire the other's lock. Fortunately, this can be avoided with careful programming and structured lock-taking, as we'll see. So, it's important to minimise where locks are used to maximise the concurrency and performance of the collection. Implementation As you might expect, ConcurrentDictionary is similar in basic implementation to the non-concurrent Dictionary, which I studied in a previous post. I'll be using some concepts introduced there, so I recommend you have a quick read of it. So, if you were implementing a thread-safe dictionary, what would you do? The naive implementation is to simply have a single lock around all methods accessing the dictionary. This would work, but doesn't allow much concurrency. Fortunately, the bucketing used by Dictionary allows a simple but effective improvement to this - one lock per bucket. This allows different threads modifying different buckets to do so in parallel. Any thread making changes to the contents of a bucket takes the lock for that bucket, ensuring those changes are thread-safe. The method that maps each bucket to a lock is the GetBucketAndLockNo method: private void GetBucketAndLockNo( int hashcode, out int bucketNo, out int lockNo, int bucketCount) { // the bucket number is the hashcode (without the initial sign bit) // modulo the number of buckets bucketNo = (hashcode & 0x7fffffff) % bucketCount; // and the lock number is the bucket number modulo the number of locks lockNo = bucketNo % m_locks.Length; } However, this does require some changes to how the buckets are implemented. The 'implicit' linked list within a single backing array used by the non-concurrent Dictionary adds a dependency between separate buckets, as every bucket uses the same backing array. Instead, ConcurrentDictionary uses a strict linked list on each bucket: This ensures that each bucket is entirely separate from all other buckets; adding or removing an item from a bucket is independent to any changes to other buckets. Modifying the dictionary All the operations on the dictionary follow the same basic pattern: void AlterBucket(TKey key, ...) { int bucketNo, lockNo; 1: GetBucketAndLockNo( key.GetHashCode(), out bucketNo, out lockNo, m_buckets.Length); 2: lock (m_locks[lockNo]) { 3: Node headNode = m_buckets[bucketNo]; 4: Mutate the node linked list as appropriate } } For example, when adding another entry to the dictionary, you would iterate through the linked list to check whether the key exists already, and add the new entry as the head node. When removing items, you would find the entry to remove (if it exists), and remove the node from the linked list. Adding, updating, and removing items all follow this pattern. Performance issues There is a problem we have to address at this point. If the number of buckets in the dictionary is fixed in the constructor, then the performance will degrade from O(1) to O(n) when a large number of items are added to the dictionary. As more and more items get added to the linked lists in each bucket, the lookup operations will spend most of their time traversing a linear linked list. To fix this, the buckets array has to be resized once the number of items in each bucket has gone over a certain limit. (In ConcurrentDictionary this limit is when the size of the largest bucket is greater than the number of buckets for each lock. This check is done at the end of the TryAddInternal method.) Resizing the bucket array and re-hashing everything affects every bucket in the collection. Therefore, this operation needs to take out every lock in the collection. Taking out mutiple locks at once inevitably summons the spectre of the deadlock; two threads each hold a lock, and each trying to acquire the other lock. How can we eliminate this? Simple - ensure that threads never try to 'swap' locks in this fashion. When taking out multiple locks, always take them out in the same order, and always take out all the locks you need before starting to release them. In ConcurrentDictionary, this is controlled by the AcquireLocks, AcquireAllLocks and ReleaseLocks methods. Locks are always taken out and released in the order they are in the m_locks array, and locks are all released right at the end of the method in a finally block. At this point, it's worth pointing out that the locks array is never re-assigned, even when the buckets array is increased in size. The number of locks is fixed in the constructor by the concurrencyLevel parameter. This simplifies programming the locks; you don't have to check if the locks array has changed or been re-assigned before taking out a lock object. And you can be sure that when a thread takes out a lock, another thread isn't going to re-assign the lock array. This would create a new series of lock objects, thus allowing another thread to ignore the existing locks (and any threads controlling them), breaking thread-safety. Consequences of growing the array Just because we're using locks doesn't mean that race conditions aren't a problem. We can see this by looking at the GrowTable method. The operation of this method can be boiled down to: private void GrowTable(Node[] buckets) { try { 1: Acquire first lock in the locks array // this causes any other thread trying to take out // all the locks to block because the first lock in the array // is always the one taken out first // check if another thread has already resized the buckets array // while we were waiting to acquire the first lock 2: if (buckets != m_buckets) return; 3: Calculate the new size of the backing array 4: Node[] array = new array[size]; 5: Acquire all the remaining locks 6: Re-hash the contents of the existing buckets into array 7: m_buckets = array; } finally { 8: Release all locks } } As you can see, there's already a check for a race condition at step 2, for the case when the GrowTable method is called twice in quick succession on two separate threads. One will successfully resize the buckets array (blocking the second in the meantime), when the second thread is unblocked it'll see that the array has already been resized & exit without doing anything. There is another case we need to consider; looking back at the AlterBucket method above, consider the following situation: Thread 1 calls AlterBucket; step 1 is executed to get the bucket and lock numbers. Thread 2 calls GrowTable and executes steps 1-5; thread 1 is blocked when it tries to take out the lock in step 2. Thread 2 re-hashes everything, re-assigns the buckets array, and releases all the locks (steps 6-8). Thread 1 is unblocked and continues executing, but the calculated bucket and lock numbers are no longer valid. Between calculating the correct bucket and lock number and taking out the lock, another thread has changed where everything is. Not exactly thread-safe. Well, a similar problem was solved in ConcurrentStack and ConcurrentQueue by storing a local copy of the state, doing the necessary calculations, then checking if that state is still valid. We can use a similar idea here: void AlterBucket(TKey key, ...) { while (true) { Node[] buckets = m_buckets; int bucketNo, lockNo; GetBucketAndLockNo( key.GetHashCode(), out bucketNo, out lockNo, buckets.Length); lock (m_locks[lockNo]) { // if the state has changed, go back to the start if (buckets != m_buckets) continue; Node headNode = m_buckets[bucketNo]; Mutate the node linked list as appropriate } break; } } TryGetValue and GetEnumerator And so, finally, we get onto TryGetValue and GetEnumerator. I've left these to the end because, well, they don't actually use any locks. How can this be? Whenever you change a bucket, you need to take out the corresponding lock, yes? Indeed you do. However, it is important to note that TryGetValue and GetEnumerator don't actually change anything. Just as immutable objects are, by definition, thread-safe, read-only operations don't need to take out a lock because they don't change anything. All lockless methods can happily iterate through the buckets and linked lists without worrying about locking anything. However, this does put restrictions on how the other methods operate. Because there could be another thread in the middle of reading the dictionary at any time (even if a lock is taken out), the dictionary has to be in a valid state at all times. Every change to state has to be made visible to other threads in a single atomic operation (all relevant variables are marked volatile to help with this). This restriction ensures that whatever the reading threads are doing, they never read the dictionary in an invalid state (eg items that should be in the collection temporarily removed from the linked list, or reading a node that has had it's key & value removed before the node itself has been removed from the linked list). Fortunately, all the operations needed to change the dictionary can be done in that way. Bucket resizes are made visible when the new array is assigned back to the m_buckets variable. Any additions or modifications to a node are done by creating a new node, then splicing it into the existing list using a single variable assignment. Node removals are simply done by re-assigning the node's m_next pointer. Because the dictionary can be changed by another thread during execution of the lockless methods, the GetEnumerator method is liable to return dirty reads - changes made to the dictionary after GetEnumerator was called, but before the enumeration got to that point in the dictionary. It's worth listing at this point which methods are lockless, and which take out all the locks in the dictionary to ensure they get a consistent view of the dictionary: Lockless: TryGetValue GetEnumerator The indexer getter ContainsKey Takes out every lock (lockfull?): Count IsEmpty Keys Values CopyTo ToArray Concurrent principles That covers the overall implementation of ConcurrentDictionary. I haven't even begun to scratch the surface of this sophisticated collection. That I leave to you. However, we've looked at enough to be able to extract some useful principles for concurrent programming: Partitioning When using locks, the work is partitioned into independant chunks, each with its own lock. Each partition can then be modified concurrently to other partitions. Ordered lock-taking When a method does need to control the entire collection, locks are taken and released in a fixed order to prevent deadlocks. Lockless reads Read operations that don't care about dirty reads don't take out any lock; the rest of the collection is implemented so that any reading thread always has a consistent view of the collection. That leads us to the final collection in this little series - ConcurrentBag. Lacking a non-concurrent analogy, it is quite different to any other collection in the class libraries. Prepare your thinking hats!

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• C#/.NET Little Wonders: Interlocked CompareExchange()

  - by James Michael Hare

  Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Two posts ago, I discussed the Interlocked Add(), Increment(), and Decrement() methods (here) for adding and subtracting values in a thread-safe, lightweight manner.  Then, last post I talked about the Interlocked Read() and Exchange() methods (here) for safely and efficiently reading and setting 32 or 64 bit values (or references).  This week, we’ll round out the discussion by talking about the Interlocked CompareExchange() method and how it can be put to use to exchange a value if the current value is what you expected it to be. Dirty reads can lead to bad results Many of the uses of Interlocked that we’ve explored so far have centered around either reading, setting, or adding values.  But what happens if you want to do something more complex such as setting a value based on the previous value in some manner? Perhaps you were creating an application that reads a current balance, applies a deposit, and then saves the new modified balance, where of course you’d want that to happen atomically.  If you read the balance, then go to save the new balance and between that time the previous balance has already changed, you’ll have an issue!  Think about it, if we read the current balance as $400, and we are applying a new deposit of $50.75, but meanwhile someone else deposits $200 and sets the total to $600, but then we write a total of $450.75 we’ve lost $200! Now, certainly for int and long values we can use Interlocked.Add() to handles these cases, and it works well for that.  But what if we want to work with doubles, for example?  Let’s say we wanted to add the numbers from 0 to 99,999 in parallel.  We could do this by spawning several parallel tasks to continuously add to a total: 1: double total = 0; 2:  3: Parallel.For(0, 10000, next => 4: { 5: total += next; 6: }); Were this run on one thread using a standard for loop, we’d expect an answer of 4,999,950,000 (the sum of all numbers from 0 to 99,999).  But when we run this in parallel as written above, we’ll likely get something far off.  The result of one of my runs, for example, was 1,281,880,740.  That is way off!  If this were banking software we’d be in big trouble with our clients.  So what happened?  The += operator is not atomic, it will read in the current value, add the result, then store it back into the total.  At any point in all of this another thread could read a “dirty” current total and accidentally “skip” our add.   So, to clean this up, we could use a lock to guarantee concurrency: 1: double total = 0.0; 2: object locker = new object(); 3:  4: Parallel.For(0, count, next => 5: { 6: lock (locker) 7: { 8: total += next; 9: } 10: }); Which will give us the correct result of 4,999,950,000.  One thing to note is that locking can be heavy, especially if the operation being locked over is trivial, or the life of the lock is a high percentage of the work being performed concurrently.  In the case above, the lock consumes pretty much all of the time of each parallel task – and the task being locked on is relatively trivial. Now, let me put in a disclaimer here before we go further: For most uses, lock is more than sufficient for your needs, and is often the simplest solution!    So, if lock is sufficient for most needs, why would we ever consider another solution?  The problem with locking is that it can suspend execution of your thread while it waits for the signal that the lock is free.  Moreover, if the operation being locked over is trivial, the lock can add a very high level of overhead.  This is why things like Interlocked.Increment() perform so well, instead of locking just to perform an increment, we perform the increment with an atomic, lockless method. As with all things performance related, it’s important to profile before jumping to the conclusion that you should optimize everything in your path.  If your profiling shows that locking is causing a high level of waiting in your application, then it’s time to consider lighter alternatives such as Interlocked. CompareExchange() – Exchange existing value if equal some value So let’s look at how we could use CompareExchange() to solve our problem above.  The general syntax of CompareExchange() is: T CompareExchange<T>(ref T location, T newValue, T expectedValue) If the value in location == expectedValue, then newValue is exchanged.  Either way, the value in location (before exchange) is returned. Actually, CompareExchange() is not one method, but a family of overloaded methods that can take int, long, float, double, pointers, or references.  It cannot take other value types (that is, can’t CompareExchange() two DateTime instances directly).  Also keep in mind that the version that takes any reference type (the generic overload) only checks for reference equality, it does not call any overridden Equals(). So how does this help us?  Well, we can grab the current total, and exchange the new value if total hasn’t changed.  This would look like this: 1: // grab the snapshot 2: double current = total; 3:  4: // if the total hasn’t changed since I grabbed the snapshot, then 5: // set it to the new total 6: Interlocked.CompareExchange(ref total, current + next, current); So what the code above says is: if the amount in total (1st arg) is the same as the amount in current (3rd arg), then set total to current + next (2nd arg).  This check and exchange pair is atomic (and thus thread-safe). This works if total is the same as our snapshot in current, but the problem, is what happens if they aren’t the same?  Well, we know that in either case we will get the previous value of total (before the exchange), back as a result.  Thus, we can test this against our snapshot to see if it was the value we expected: 1: // if the value returned is != current, then our snapshot must be out of date 2: // which means we didn't (and shouldn't) apply current + next 3: if (Interlocked.CompareExchange(ref total, current + next, current) != current) 4: { 5: // ooops, total was not equal to our snapshot in current, what should we do??? 6: } So what do we do if we fail?  That’s up to you and the problem you are trying to solve.  It’s possible you would decide to abort the whole transaction, or perhaps do a lightweight spin and try again.  Let’s try that: 1: double current = total; 2:  3: // make first attempt... 4: if (Interlocked.CompareExchange(ref total, current + i, current) != current) 5: { 6: // if we fail, go into a spin wait, spin, and try again until succeed 7: var spinner = new SpinWait(); 8:  9: do 10: { 11: spinner.SpinOnce(); 12: current = total; 13: } 14: while (Interlocked.CompareExchange(ref total, current + i, current) != current); 15: } 16:  This is not trivial code, but it illustrates a possible use of CompareExchange().  What we are doing is first checking to see if we succeed on the first try, and if so great!  If not, we create a SpinWait and then repeat the process of SpinOnce(), grab a fresh snapshot, and repeat until CompareExchnage() succeeds.  You may wonder why not a simple do-while here, and the reason it’s more efficient to only create the SpinWait until we absolutely know we need one, for optimal efficiency. Though not as simple (or maintainable) as a simple lock, this will perform better in many situations.  Comparing an unlocked (and wrong) version, a version using lock, and the Interlocked of the code, we get the following average times for multiple iterations of adding the sum of 100,000 numbers: 1: Unlocked money average time: 2.1 ms 2: Locked money average time: 5.1 ms 3: Interlocked money average time: 3 ms So the Interlocked.CompareExchange(), while heavier to code, came in lighter than the lock, offering a good compromise of safety and performance when we need to reduce contention. CompareExchange() - it’s not just for adding stuff… So that was one simple use of CompareExchange() in the context of adding double values -- which meant we couldn’t have used the simpler Interlocked.Add() -- but it has other uses as well. If you think about it, this really works anytime you want to create something new based on a current value without using a full lock.  For example, you could use it to create a simple lazy instantiation implementation.  In this case, we want to set the lazy instance only if the previous value was null: 1: public static class Lazy<T> where T : class, new() 2: { 3: private static T _instance; 4:  5: public static T Instance 6: { 7: get 8: { 9: // if current is null, we need to create new instance 10: if (_instance == null) 11: { 12: // attempt create, it will only set if previous was null 13: Interlocked.CompareExchange(ref _instance, new T(), (T)null); 14: } 15:  16: return _instance; 17: } 18: } 19: } So, if _instance == null, this will create a new T() and attempt to exchange it with _instance.  If _instance is not null, then it does nothing and we discard the new T() we created. This is a way to create lazy instances of a type where we are more concerned about locking overhead than creating an accidental duplicate which is not used.  In fact, the BCL implementation of Lazy<T> offers a similar thread-safety choice for Publication thread safety, where it will not guarantee only one instance was created, but it will guarantee that all readers get the same instance.  Another possible use would be in concurrent collections.  Let’s say, for example, that you are creating your own brand new super stack that uses a linked list paradigm and is “lock free”.  We could use Interlocked.CompareExchange() to be able to do a lockless Push() which could be more efficient in multi-threaded applications where several threads are pushing and popping on the stack concurrently. Yes, there are already concurrent collections in the BCL (in .NET 4.0 as part of the TPL), but it’s a fun exercise!  So let’s assume we have a node like this: 1: public sealed class Node<T> 2: { 3: // the data for this node 4: public T Data { get; set; } 5:  6: // the link to the next instance 7: internal Node<T> Next { get; set; } 8: } Then, perhaps, our stack’s Push() operation might look something like: 1: public sealed class SuperStack<T> 2: { 3: private volatile T _head; 4:  5: public void Push(T value) 6: { 7: var newNode = new Node<int> { Data = value, Next = _head }; 8:  9: if (Interlocked.CompareExchange(ref _head, newNode, newNode.Next) != newNode.Next) 10: { 11: var spinner = new SpinWait(); 12:  13: do 14: { 15: spinner.SpinOnce(); 16: newNode.Next = _head; 17: } 18: while (Interlocked.CompareExchange(ref _head, newNode, newNode.Next) != newNode.Next); 19: } 20: } 21:  22: // ... 23: } Notice a similar paradigm here as with adding our doubles before.  What we are doing is creating the new Node with the data to push, and with a Next value being the original node referenced by _head.  This will create our stack behavior (LIFO – Last In, First Out).  Now, we have to set _head to now refer to the newNode, but we must first make sure it hasn’t changed! So we check to see if _head has the same value we saved in our snapshot as newNode.Next, and if so, we set _head to newNode.  This is all done atomically, and the result is _head’s original value, as long as the original value was what we assumed it was with newNode.Next, then we are good and we set it without a lock!  If not, we SpinWait and try again. Once again, this is much lighter than locking in highly parallelized code with lots of contention.  If I compare the method above with a similar class using lock, I get the following results for pushing 100,000 items: 1: Locked SuperStack average time: 6 ms 2: Interlocked SuperStack average time: 4.5 ms So, once again, we can get more efficient than a lock, though there is the cost of added code complexity.  Fortunately for you, most of the concurrent collection you’d ever need are already created for you in the System.Collections.Concurrent (here) namespace – for more information, see my Little Wonders – The Concurent Collections Part 1 (here), Part 2 (here), and Part 3 (here). Summary We’ve seen before how the Interlocked class can be used to safely and efficiently add, increment, decrement, read, and exchange values in a multi-threaded environment.  In addition to these, Interlocked CompareExchange() can be used to perform more complex logic without the need of a lock when lock contention is a concern. The added efficiency, though, comes at the cost of more complex code.  As such, the standard lock is often sufficient for most thread-safety needs.  But if profiling indicates you spend a lot of time waiting for locks, or if you just need a lock for something simple such as an increment, decrement, read, exchange, etc., then consider using the Interlocked class’s methods to reduce wait. Technorati Tags: C#,CSharp,.NET,Little Wonders,Interlocked,CompareExchange,threading,concurrency

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• Problem calling linux C code from FIQ handler

  - by fastmonkeywheels

  I'm working on an armv6 core and have an FIQ hander that works great when I do all of my work in it. However I need to branch to some additional code that's too large for the FIQ memory area. The FIQ handler gets copied from fiq_start to fiq_end to 0xFFFF001C when registered static void test_fiq_handler(void) { asm volatile("\ .global fiq_start\n\ fiq_start:"); // clear gpio irq asm("ldr r10, GPIO_BASE_ISR"); asm("ldr r9, [r10]"); asm("orr r9, #0x04"); asm("str r9, [r10]"); // clear force register asm("ldr r10, AVIC_BASE_INTFRCH"); asm("ldr r9, [r10]"); asm("mov r9, #0"); asm("str r9, [r10]"); // prepare branch register asm(" ldr r11, fiq_handler"); // save all registers, build sp and branch to C asm(" adr r9, regpool"); asm(" stmia r9, {r0 - r8, r14}"); asm(" adr sp, fiq_sp"); asm(" ldr sp, [sp]"); asm(" add lr, pc,#4"); asm(" mov pc, r11"); #if 0 asm("ldr r10, IOMUX_ADDR12"); asm("ldr r9, [r10]"); asm("orr r9, #0x08 @ top/vertex LED"); asm("str r9,[r10] @turn on LED"); asm("bic r9, #0x08 @ top/vertex LED"); asm("str r9,[r10] @turn on LED"); #endif asm(" adr r9, regpool"); asm(" ldmia r9, {r0 - r8, r14}"); // return asm("subs pc, r14, #4"); asm("IOMUX_ADDR12: .word 0xFC2A4000"); asm("AVIC_BASE_INTCNTL: .word 0xFC400000"); asm("AVIC_BASE_INTENNUM: .word 0xFC400008"); asm("AVIC_BASE_INTDISNUM: .word 0xFC40000C"); asm("AVIC_BASE_FIVECSR: .word 0xFC400044"); asm("AVIC_BASE_INTFRCH: .word 0xFC400050"); asm("GPIO_BASE_ISR: .word 0xFC2CC018"); asm(".globl fiq_handler"); asm("fiq_sp: .long fiq_stack+120"); asm("fiq_handler: .long 0"); asm("regpool: .space 40"); asm(".pool"); asm(".align 5"); asm("fiq_stack: .space 124"); asm(".global fiq_end"); asm("fiq_end:"); } fiq_hander gets set to the following function: static void fiq_flip_pins(void) { asm("ldr r10, IOMUX_ADDR12_k"); asm("ldr r9, [r10]"); asm("orr r9, #0x08 @ top/vertex LED"); asm("str r9,[r10] @turn on LED"); asm("bic r9, #0x08 @ top/vertex LED"); asm("str r9,[r10] @turn on LED"); asm("IOMUX_ADDR12_k: .word 0xFC2A4000"); } EXPORT_SYMBOL(fiq_flip_pins); I know that since the FIQ handler operates outside of any normal kernel API's and that it is a rather high priority interrupt I must ensure that whatever I call is already swapped into memory. I do this by having the fiq_flip_pins function defined in the monolithic kernel and not as a module which gets vmalloc. If I don't branch to the fiq_flip_pins function, and instead do the work in the test_fiq_handler function everything works as expected. It's the branching that's causing me problems at the moment. Right after branching I get a kernel panic about a paging request. I don't understand why I'm getting the paging request. fiq_flip_pins is in the kernel at: c00307ec t fiq_flip_pins Unable to handle kernel paging request at virtual address 736e6f63 pgd = c3dd0000 [736e6f63] *pgd=00000000 Internal error: Oops: 5 [#1] PREEMPT Modules linked in: hello_1 CPU: 0 Not tainted (2.6.31-207-g7286c01-svn4 #122) PC is at strnlen+0x10/0x28 LR is at string+0x38/0xcc pc : [<c016b004>] lr : [<c016c754>] psr: a00001d3 sp : c3817ea0 ip : 736e6f63 fp : 00000400 r10: c03cab5c r9 : c0339ae0 r8 : 736e6f63 r7 : c03caf5c r6 : c03cab6b r5 : ffffffff r4 : 00000000 r3 : 00000004 r2 : 00000000 r1 : ffffffff r0 : 736e6f63 Flags: NzCv IRQs off FIQs off Mode SVC_32 ISA ARM Segment user Control: 00c5387d Table: 83dd0008 DAC: 00000015 Process sh (pid: 1663, stack limit = 0xc3816268) Stack: (0xc3817ea0 to 0xc3818000) Since there are no API calls in my code I have to assume that something is going wrong in the C call and back. Any help solving this is appreciated.

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• Of these 3 methods for reading linked lists from shared memory, why is the 3rd fastest?

  - by Joseph Garvin

  I have a 'server' program that updates many linked lists in shared memory in response to external events. I want client programs to notice an update on any of the lists as quickly as possible (lowest latency). The server marks a linked list's node's state_ as FILLED once its data is filled in and its next pointer has been set to a valid location. Until then, its state_ is NOT_FILLED_YET. I am using memory barriers to make sure that clients don't see the state_ as FILLED before the data within is actually ready (and it seems to work, I never see corrupt data). Also, state_ is volatile to be sure the compiler doesn't lift the client's checking of it out of loops. Keeping the server code exactly the same, I've come up with 3 different methods for the client to scan the linked lists for changes. The question is: Why is the 3rd method fastest? Method 1: Round robin over all the linked lists (called 'channels') continuously, looking to see if any nodes have changed to 'FILLED': void method_one() { std::vector<Data*> channel_cursors; for(ChannelList::iterator i = channel_list.begin(); i != channel_list.end(); ++i) { Data* current_item = static_cast<Data*>(i->get(segment)->tail_.get(segment)); channel_cursors.push_back(current_item); } while(true) { for(std::size_t i = 0; i < channel_list.size(); ++i) { Data* current_item = channel_cursors[i]; ACQUIRE_MEMORY_BARRIER; if(current_item->state_ == NOT_FILLED_YET) { continue; } log_latency(current_item->tv_sec_, current_item->tv_usec_); channel_cursors[i] = static_cast<Data*>(current_item->next_.get(segment)); } } } Method 1 gave very low latency when then number of channels was small. But when the number of channels grew (250K+) it became very slow because of looping over all the channels. So I tried... Method 2: Give each linked list an ID. Keep a separate 'update list' to the side. Every time one of the linked lists is updated, push its ID on to the update list. Now we just need to monitor the single update list, and check the IDs we get from it. void method_two() { std::vector<Data*> channel_cursors; for(ChannelList::iterator i = channel_list.begin(); i != channel_list.end(); ++i) { Data* current_item = static_cast<Data*>(i->get(segment)->tail_.get(segment)); channel_cursors.push_back(current_item); } UpdateID* update_cursor = static_cast<UpdateID*>(update_channel.tail_.get(segment)); while(true) { if(update_cursor->state_ == NOT_FILLED_YET) { continue; } ::uint32_t update_id = update_cursor->list_id_; Data* current_item = channel_cursors[update_id]; if(current_item->state_ == NOT_FILLED_YET) { std::cerr << "This should never print." << std::endl; // it doesn't continue; } log_latency(current_item->tv_sec_, current_item->tv_usec_); channel_cursors[update_id] = static_cast<Data*>(current_item->next_.get(segment)); update_cursor = static_cast<UpdateID*>(update_cursor->next_.get(segment)); } } Method 2 gave TERRIBLE latency. Whereas Method 1 might give under 10us latency, Method 2 would inexplicably often given 8ms latency! Using gettimeofday it appears that the change in update_cursor-state_ was very slow to propogate from the server's view to the client's (I'm on a multicore box, so I assume the delay is due to cache). So I tried a hybrid approach... Method 3: Keep the update list. But loop over all the channels continuously, and within each iteration check if the update list has updated. If it has, go with the number pushed onto it. If it hasn't, check the channel we've currently iterated to. void method_three() { std::vector<Data*> channel_cursors; for(ChannelList::iterator i = channel_list.begin(); i != channel_list.end(); ++i) { Data* current_item = static_cast<Data*>(i->get(segment)->tail_.get(segment)); channel_cursors.push_back(current_item); } UpdateID* update_cursor = static_cast<UpdateID*>(update_channel.tail_.get(segment)); while(true) { for(std::size_t i = 0; i < channel_list.size(); ++i) { std::size_t idx = i; ACQUIRE_MEMORY_BARRIER; if(update_cursor->state_ != NOT_FILLED_YET) { //std::cerr << "Found via update" << std::endl; i--; idx = update_cursor->list_id_; update_cursor = static_cast<UpdateID*>(update_cursor->next_.get(segment)); } Data* current_item = channel_cursors[idx]; ACQUIRE_MEMORY_BARRIER; if(current_item->state_ == NOT_FILLED_YET) { continue; } found_an_update = true; log_latency(current_item->tv_sec_, current_item->tv_usec_); channel_cursors[idx] = static_cast<Data*>(current_item->next_.get(segment)); } } } The latency of this method was as good as Method 1, but scaled to large numbers of channels. The problem is, I have no clue why. Just to throw a wrench in things: if I uncomment the 'found via update' part, it prints between EVERY LATENCY LOG MESSAGE. Which means things are only ever found on the update list! So I don't understand how this method can be faster than method 2. The full, compilable code (requires GCC and boost-1.41) that generates random strings as test data is at: http://pastebin.com/e3HuL0nr

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• (C++) Linking with namespaces causes duplicate symbol error

  - by user577072

  Hello. For the past few days, I have been trying to figure out how to link the files for a CLI gaming project I have been working on. There are two halves of the project, the Client and the Server code. The client needs two libraries I've made. The first is a general purpose game board. This is split between GameEngine.h and GameEngine.cpp. The header file looks something like this namespace gfdGaming { // struct sqr_size { // Index x; // Index y; // }; typedef struct { Index x, y; } sqr_size; const sqr_size sPos = {1, 1}; sqr_size sqr(Index x, Index y); sqr_size ePos; class board { // Prototypes / declarations for the class } } And the CPP file is just giving everything content #include "GameEngine.h" type gfdGaming::board::functions The client also has game-specific code (in this case, TicTacToe) split into declarations and definitions (TTT.h, Client.cpp). TTT.h is basically #include "GameEngine.h" #define TTTtar "localhost" #define TTTport 2886 using namespace gfdGaming; void* turnHandler(void*); namespace nsTicTacToe { GFDCON gfd; const char X = 'X'; const char O = 'O'; string MPhostname, mySID; board TTTboard; bool PlayerIsX = true, isMyTurn; char Player = X, Player2 = O; int recon(string* datHolder = NULL, bool force = false); void initMP(bool create = false, string hn = TTTtar); void init(); bool isTie(); int turnPlayer(Index loc, char lSym = Player); bool checkWin(char sym = Player); int mainloop(); int mainloopMP(); }; // NS I made the decision to put this in a namespace to group it instead of a class because there are some parts that would not work well in OOP, and it's much easier to implement later on. I have had trouble linking the client in the past, but this setup seems to work. My server is also split into two files, Server.h and Server.cpp. Server.h contains exactly: #include "../TicTacToe/TTT.h" // Server needs a full copy of TicTacToe code class TTTserv; struct TTTachievement_requirement { Index id; Index loc; bool inUse; }; struct TTTachievement_t { Index id; bool achieved; bool AND, inSameGame; bool inUse; bool (*lHandler)(TTTserv*); char mustBeSym; int mustBePlayer; string name, description; TTTachievement_requirement steps[safearray(8*8)]; }; class achievement_core_t : public GfdOogleTech { public: // May be shifted to private TTTachievement_t list[safearray(8*8)]; public: achievement_core_t(); int insert(string name, string d, bool samegame, bool lAnd, int lSteps[8*8], int mbP=0, char mbS=0); }; struct TTTplayer_t { Index id; bool inUse; string ip, sessionID; char sym; int desc; TTTachievement_t Ding[8*8]; }; struct TTTgame_t { TTTplayer_t Player[safearray(2)]; TTTplayer_t Spectator; achievement_core_t achievement_core; Index cTurn, players; port_t roomLoc; bool inGame, Xused, Oused, newEvent; }; class TTTserv : public gSserver { TTTgame_t Game; TTTplayer_t *cPlayer; port_t conPort; public: achievement_core_t *achiev; thread threads[8]; int parseit(string tDat, string tsIP); Index conCount; int parseit(string tDat, int tlUser, TTTplayer_t** retval); private: int parseProto(string dat, string sIP); int parseProto(string dat, int lUser); int cycleTurn(); void setup(port_t lPort = 0, bool complete = false); public: int newEvent; TTTserv(port_t tlPort = TTTport, bool tcomplete = true); TTTplayer_t* userDC(Index id, Index force = false); int sendToPlayers(string dat, bool asMSG = false); int mainLoop(volatile bool *play); }; // Other void* userHandler(void*); void* handleUser(void*); And in the CPP file I include Server.h and provide main() and the contents of all functions previously declared. Now to the problem at hand I am having issues when linking my server. More specifically, I get a duplicate symbol error for every variable in nsTicTacToe (and possibly in gfdGaming as well). Since I need the TicTacToe functions, I link Client.cpp ( without main() ) when building the server ld: duplicate symbol nsTicTacToe::PlayerIsX in Client.o and Server.o collect2: ld returned 1 exit status Command /Developer/usr/bin/g++-4.2 failed with exit code 1 It stops once a problem is encountered, but if PlayerIsX is removed / changed temporarily than another variable causes an error Essentially, I am looking for any advice on how to better organize my code to hopefully fix these errors. Disclaimers: -I apologize in advance if I provided too much or too little information, as it is my first time posting -I have tried using static and extern to fix these problems, but apparently those are not what I need Thank you to anyone who takes the time to read all of this and respond =)

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• Toorcon 15 (2013)

  - by danx

  The Toorcon gang (senior staff): h1kari (founder), nfiltr8, and Geo Introduction to Toorcon 15 (2013) A Tale of One Software Bypass of MS Windows 8 Secure Boot Breaching SSL, One Byte at a Time Running at 99%: Surviving an Application DoS Security Response in the Age of Mass Customized Attacks x86 Rewriting: Defeating RoP and other Shinanighans Clowntown Express: interesting bugs and running a bug bounty program Active Fingerprinting of Encrypted VPNs Making Attacks Go Backwards Mask Your Checksums—The Gorry Details Adventures with weird machines thirty years after "Reflections on Trusting Trust" Introduction to Toorcon 15 (2013) Toorcon 15 is the 15th annual security conference held in San Diego. I've attended about a third of them and blogged about previous conferences I attended here starting in 2003. As always, I've only summarized the talks I attended and interested me enough to write about them. Be aware that I may have misrepresented the speaker's remarks and that they are not my remarks or opinion, or those of my employer, so don't quote me or them. Those seeking further details may contact the speakers directly or use The Google. For some talks, I have a URL for further information. A Tale of One Software Bypass of MS Windows 8 Secure Boot Andrew Furtak and Oleksandr Bazhaniuk Yuri Bulygin, Oleksandr ("Alex") Bazhaniuk, and (not present) Andrew Furtak Yuri and Alex talked about UEFI and Bootkits and bypassing MS Windows 8 Secure Boot, with vendor recommendations. They previously gave this talk at the BlackHat 2013 conference. MS Windows 8 Secure Boot Overview UEFI (Unified Extensible Firmware Interface) is interface between hardware and OS. UEFI is processor and architecture independent. Malware can replace bootloader (bootx64.efi, bootmgfw.efi). Once replaced can modify kernel. Trivial to replace bootloader. Today many legacy bootkits—UEFI replaces them most of them. MS Windows 8 Secure Boot verifies everything you load, either through signatures or hashes. UEFI firmware relies on secure update (with signed update). You would think Secure Boot would rely on ROM (such as used for phones0, but you can't do that for PCs—PCs use writable memory with signatures DXE core verifies the UEFI boat loader(s) OS Loader (winload.efi, winresume.efi) verifies the OS kernel A chain of trust is established with a root key (Platform Key, PK), which is a cert belonging to the platform vendor. Key Exchange Keys (KEKs) verify an "authorized" database (db), and "forbidden" database (dbx). X.509 certs with SHA-1/SHA-256 hashes. Keys are stored in non-volatile (NV) flash-based NVRAM. Boot Services (BS) allow adding/deleting keys (can't be accessed once OS starts—which uses Run-Time (RT)). Root cert uses RSA-2048 public keys and PKCS#7 format signatures. SecureBoot — enable disable image signature checks SetupMode — update keys, self-signed keys, and secure boot variables CustomMode — allows updating keys Secure Boot policy settings are: always execute, never execute, allow execute on security violation, defer execute on security violation, deny execute on security violation, query user on security violation Attacking MS Windows 8 Secure Boot Secure Boot does NOT protect from physical access. Can disable from console. Each BIOS vendor implements Secure Boot differently. There are several platform and BIOS vendors. It becomes a "zoo" of implementations—which can be taken advantage of. Secure Boot is secure only when all vendors implement it correctly. Allow only UEFI firmware signed updates protect UEFI firmware from direct modification in flash memory protect FW update components program SPI controller securely protect secure boot policy settings in nvram protect runtime api disable compatibility support module which allows unsigned legacy Can corrupt the Platform Key (PK) EFI root certificate variable in SPI flash. If PK is not found, FW enters setup mode wich secure boot turned off. Can also exploit TPM in a similar manner. One is not supposed to be able to directly modify the PK in SPI flash from the OS though. But they found a bug that they can exploit from User Mode (undisclosed) and demoed the exploit. It loaded and ran their own bootkit. The exploit requires a reboot. Multiple vendors are vulnerable. They will disclose this exploit to vendors in the future. Recommendations: allow only signed updates protect UEFI fw in ROM protect EFI variable store in ROM Breaching SSL, One Byte at a Time Yoel Gluck and Angelo Prado Angelo Prado and Yoel Gluck, Salesforce.com CRIME is software that performs a "compression oracle attack." This is possible because the SSL protocol doesn't hide length, and because SSL compresses the header. CRIME requests with every possible character and measures the ciphertext length. Look for the plaintext which compresses the most and looks for the cookie one byte-at-a-time. SSL Compression uses LZ77 to reduce redundancy. Huffman coding replaces common byte sequences with shorter codes. US CERT thinks the SSL compression problem is fixed, but it isn't. They convinced CERT that it wasn't fixed and they issued a CVE. BREACH, breachattrack.com BREACH exploits the SSL response body (Accept-Encoding response, Content-Encoding). It takes advantage of the fact that the response is not compressed. BREACH uses gzip and needs fairly "stable" pages that are static for ~30 seconds. It needs attacker-supplied content (say from a web form or added to a URL parameter). BREACH listens to a session's requests and responses, then inserts extra requests and responses. Eventually, BREACH guesses a session's secret key. Can use compression to guess contents one byte at-a-time. For example, "Supersecret SupersecreX" (a wrong guess) compresses 10 bytes, and "Supersecret Supersecret" (a correct guess) compresses 11 bytes, so it can find each character by guessing every character. To start the guess, BREACH needs at least three known initial characters in the response sequence. Compression length then "leaks" information. Some roadblocks include no winners (all guesses wrong) or too many winners (multiple possibilities that compress the same). The solutions include: lookahead (guess 2 or 3 characters at-a-time instead of 1 character). Expensive rollback to last known conflict check compression ratio can brute-force first 3 "bootstrap" characters, if needed (expensive) block ciphers hide exact plain text length. Solution is to align response in advance to block size Mitigations length: use variable padding secrets: dynamic CSRF tokens per request secret: change over time separate secret to input-less servlets Future work eiter understand DEFLATE/GZIP HTTPS extensions Running at 99%: Surviving an Application DoS Ryan Huber Ryan Huber, Risk I/O Ryan first discussed various ways to do a denial of service (DoS) attack against web services. One usual method is to find a slow web page and do several wgets. Or download large files. Apache is not well suited at handling a large number of connections, but one can put something in front of it Can use Apache alternatives, such as nginx How to identify malicious hosts short, sudden web requests user-agent is obvious (curl, python) same url requested repeatedly no web page referer (not normal) hidden links. hide a link and see if a bot gets it restricted access if not your geo IP (unless the website is global) missing common headers in request regular timing first seen IP at beginning of attack count requests per hosts (usually a very large number) Use of captcha can mitigate attacks, but you'll lose a lot of genuine users. Bouncer, goo.gl/c2vyEc and www.github.com/rawdigits/Bouncer Bouncer is software written by Ryan in netflow. Bouncer has a small, unobtrusive footprint and detects DoS attempts. It closes blacklisted sockets immediately (not nice about it, no proper close connection). Aggregator collects requests and controls your web proxies. Need NTP on the front end web servers for clean data for use by bouncer. Bouncer is also useful for a popularity storm ("Slashdotting") and scraper storms. Future features: gzip collection data, documentation, consumer library, multitask, logging destroyed connections. Takeaways: DoS mitigation is easier with a complete picture Bouncer designed to make it easier to detect and defend DoS—not a complete cure Security Response in the Age of Mass Customized Attacks Peleus Uhley and Karthik Raman Peleus Uhley and Karthik Raman, Adobe ASSET, blogs.adobe.com/asset/ Peleus and Karthik talked about response to mass-customized exploits. Attackers behave much like a business. "Mass customization" refers to concept discussed in the book Future Perfect by Stan Davis of Harvard Business School. Mass customization is differentiating a product for an individual customer, but at a mass production price. For example, the same individual with a debit card receives basically the same customized ATM experience around the world. Or designing your own PC from commodity parts. Exploit kits are another example of mass customization. The kits support multiple browsers and plugins, allows new modules. Exploit kits are cheap and customizable. Organized gangs use exploit kits. A group at Berkeley looked at 77,000 malicious websites (Grier et al., "Manufacturing Compromise: The Emergence of Exploit-as-a-Service", 2012). They found 10,000 distinct binaries among them, but derived from only a dozen or so exploit kits. Characteristics of Mass Malware: potent, resilient, relatively low cost Technical characteristics: multiple OS, multipe payloads, multiple scenarios, multiple languages, obfuscation Response time for 0-day exploits has gone down from ~40 days 5 years ago to about ~10 days now. So the drive with malware is towards mass customized exploits, to avoid detection There's plenty of evicence that exploit development has Project Manager bureaucracy. They infer from the malware edicts to: support all versions of reader support all versions of windows support all versions of flash support all browsers write large complex, difficult to main code (8750 lines of JavaScript for example Exploits have "loose coupling" of multipe versions of software (adobe), OS, and browser. This allows specific attacks against specific versions of multiple pieces of software. Also allows exploits of more obscure software/OS/browsers and obscure versions. Gave examples of exploits that exploited 2, 3, 6, or 14 separate bugs. However, these complete exploits are more likely to be buggy or fragile in themselves and easier to defeat. Future research includes normalizing malware and Javascript. Conclusion: The coming trend is that mass-malware with mass zero-day attacks will result in mass customization of attacks. x86 Rewriting: Defeating RoP and other Shinanighans Richard Wartell Richard Wartell The attack vector we are addressing here is: First some malware causes a buffer overflow. The malware has no program access, but input access and buffer overflow code onto stack Later the stack became non-executable. The workaround malware used was to write a bogus return address to the stack jumping to malware Later came ASLR (Address Space Layout Randomization) to randomize memory layout and make addresses non-deterministic. The workaround malware used was to jump t existing code segments in the program that can be used in bad ways "RoP" is Return-oriented Programming attacks. RoP attacks use your own code and write return address on stack to (existing) expoitable code found in program ("gadgets"). Pinkie Pie was paid $60K last year for a RoP attack. One solution is using anti-RoP compilers that compile source code with NO return instructions. ASLR does not randomize address space, just "gadgets". IPR/ILR ("Instruction Location Randomization") randomizes each instruction with a virtual machine. Richard's goal was to randomize a binary with no source code access. He created "STIR" (Self-Transofrming Instruction Relocation). STIR disassembles binary and operates on "basic blocks" of code. The STIR disassembler is conservative in what to disassemble. Each basic block is moved to a random location in memory. Next, STIR writes new code sections with copies of "basic blocks" of code in randomized locations. The old code is copied and rewritten with jumps to new code. the original code sections in the file is marked non-executible. STIR has better entropy than ASLR in location of code. Makes brute force attacks much harder. STIR runs on MS Windows (PEM) and Linux (ELF). It eliminated 99.96% or more "gadgets" (i.e., moved the address). Overhead usually 5-10% on MS Windows, about 1.5-4% on Linux (but some code actually runs faster!). The unique thing about STIR is it requires no source access and the modified binary fully works! Current work is to rewrite code to enforce security policies. For example, don't create a *.{exe,msi,bat} file. Or don't connect to the network after reading from the disk. Clowntown Express: interesting bugs and running a bug bounty program Collin Greene Collin Greene, Facebook Collin talked about Facebook's bug bounty program. Background at FB: FB has good security frameworks, such as security teams, external audits, and cc'ing on diffs. But there's lots of "deep, dark, forgotten" parts of legacy FB code. Collin gave several examples of bountied bugs. Some bounty submissions were on software purchased from a third-party (but bounty claimers don't know and don't care). We use security questions, as does everyone else, but they are basically insecure (often easily discoverable). Collin didn't expect many bugs from the bounty program, but they ended getting 20+ good bugs in first 24 hours and good submissions continue to come in. Bug bounties bring people in with different perspectives, and are paid only for success. Bug bounty is a better use of a fixed amount of time and money versus just code review or static code analysis. The Bounty program started July 2011 and paid out $1.5 million to date. 14% of the submissions have been high priority problems that needed to be fixed immediately. The best bugs come from a small % of submitters (as with everything else)—the top paid submitters are paid 6 figures a year. Spammers like to backstab competitors. The youngest sumitter was 13. Some submitters have been hired. Bug bounties also allows to see bugs that were missed by tools or reviews, allowing improvement in the process. Bug bounties might not work for traditional software companies where the product has release cycle or is not on Internet. Active Fingerprinting of Encrypted VPNs Anna Shubina Anna Shubina, Dartmouth Institute for Security, Technology, and Society (I missed the start of her talk because another track went overtime. But I have the DVD of the talk, so I'll expand later) IPsec leaves fingerprints. Using netcat, one can easily visually distinguish various crypto chaining modes just from packet timing on a chart (example, DES-CBC versus AES-CBC) One can tell a lot about VPNs just from ping roundtrips (such as what router is used) Delayed packets are not informative about a network, especially if far away from the network More needed to explore about how TCP works in real life with respect to timing Making Attacks Go Backwards Fuzzynop FuzzyNop, Mandiant This talk is not about threat attribution (finding who), product solutions, politics, or sales pitches. But who are making these malware threats? It's not a single person or group—they have diverse skill levels. There's a lot of fat-fingered fumblers out there. Always look for low-hanging fruit first: "hiding" malware in the temp, recycle, or root directories creation of unnamed scheduled tasks obvious names of files and syscalls ("ClearEventLog") uncleared event logs. Clearing event log in itself, and time of clearing, is a red flag and good first clue to look for on a suspect system Reverse engineering is hard. Disassembler use takes practice and skill. A popular tool is IDA Pro, but it takes multiple interactive iterations to get a clean disassembly. Key loggers are used a lot in targeted attacks. They are typically custom code or built in a backdoor. A big tip-off is that non-printable characters need to be printed out (such as "[Ctrl]" "[RightShift]") or time stamp printf strings. Look for these in files. Presence is not proof they are used. Absence is not proof they are not used. Java exploits. Can parse jar file with idxparser.py and decomile Java file. Java typially used to target tech companies. Backdoors are the main persistence mechanism (provided externally) for malware. Also malware typically needs command and control. Application of Artificial Intelligence in Ad-Hoc Static Code Analysis John Ashaman John Ashaman, Security Innovation Initially John tried to analyze open source files with open source static analysis tools, but these showed thousands of false positives. Also tried using grep, but tis fails to find anything even mildly complex. So next John decided to write his own tool. His approach was to first generate a call graph then analyze the graph. However, the problem is that making a call graph is really hard. For example, one problem is "evil" coding techniques, such as passing function pointer. First the tool generated an Abstract Syntax Tree (AST) with the nodes created from method declarations and edges created from method use. Then the tool generated a control flow graph with the goal to find a path through the AST (a maze) from source to sink. The algorithm is to look at adjacent nodes to see if any are "scary" (a vulnerability), using heuristics for search order. The tool, called "Scat" (Static Code Analysis Tool), currently looks for C# vulnerabilities and some simple PHP. Later, he plans to add more PHP, then JSP and Java. For more information see his posts in Security Innovation blog and NRefactory on GitHub. Mask Your Checksums—The Gorry Details Eric (XlogicX) Davisson Eric (XlogicX) Davisson Sometimes in emailing or posting TCP/IP packets to analyze problems, you may want to mask the IP address. But to do this correctly, you need to mask the checksum too, or you'll leak information about the IP. Problem reports found in stackoverflow.com, sans.org, and pastebin.org are usually not masked, but a few companies do care. If only the IP is masked, the IP may be guessed from checksum (that is, it leaks data). Other parts of packet may leak more data about the IP. TCP and IP checksums both refer to the same data, so can get more bits of information out of using both checksums than just using one checksum. Also, one can usually determine the OS from the TTL field and ports in a packet header. If we get hundreds of possible results (16x each masked nibble that is unknown), one can do other things to narrow the results, such as look at packet contents for domain or geo information. With hundreds of results, can import as CSV format into a spreadsheet. Can corelate with geo data and see where each possibility is located. Eric then demoed a real email report with a masked IP packet attached. Was able to find the exact IP address, given the geo and university of the sender. Point is if you're going to mask a packet, do it right. Eric wouldn't usually bother, but do it correctly if at all, to not create a false impression of security. Adventures with weird machines thirty years after "Reflections on Trusting Trust" Sergey Bratus Sergey Bratus, Dartmouth College (and Julian Bangert and Rebecca Shapiro, not present) "Reflections on Trusting Trust" refers to Ken Thompson's classic 1984 paper. "You can't trust code that you did not totally create yourself." There's invisible links in the chain-of-trust, such as "well-installed microcode bugs" or in the compiler, and other planted bugs. Thompson showed how a compiler can introduce and propagate bugs in unmodified source. But suppose if there's no bugs and you trust the author, can you trust the code? Hell No! There's too many factors—it's Babylonian in nature. Why not? Well, Input is not well-defined/recognized (code's assumptions about "checked" input will be violated (bug/vunerabiliy). For example, HTML is recursive, but Regex checking is not recursive. Input well-formed but so complex there's no telling what it does For example, ELF file parsing is complex and has multiple ways of parsing. Input is seen differently by different pieces of program or toolchain Any Input is a program input executes on input handlers (drives state changes & transitions) only a well-defined execution model can be trusted (regex/DFA, PDA, CFG) Input handler either is a "recognizer" for the inputs as a well-defined language (see langsec.org) or it's a "virtual machine" for inputs to drive into pwn-age ELF ABI (UNIX/Linux executible file format) case study. Problems can arise from these steps (without planting bugs): compiler linker loader ld.so/rtld relocator DWARF (debugger info) exceptions The problem is you can't really automatically analyze code (it's the "halting problem" and undecidable). Only solution is to freeze code and sign it. But you can't freeze everything! Can't freeze ASLR or loading—must have tables and metadata. Any sufficiently complex input data is the same as VM byte code Example, ELF relocation entries + dynamic symbols == a Turing Complete Machine (TM). @bxsays created a Turing machine in Linux from relocation data (not code) in an ELF file. For more information, see Rebecca "bx" Shapiro's presentation from last year's Toorcon, "Programming Weird Machines with ELF Metadata" @bxsays did same thing with Mach-O bytecode Or a DWARF exception handling data .eh_frame + glibc == Turning Machine X86 MMU (IDT, GDT, TSS): used address translation to create a Turning Machine. Page handler reads and writes (on page fault) memory. Uses a page table, which can be used as Turning Machine byte code. Example on Github using this TM that will fly a glider across the screen Next Sergey talked about "Parser Differentials". That having one input format, but two parsers, will create confusion and opportunity for exploitation. For example, CSRs are parsed during creation by cert requestor and again by another parser at the CA. Another example is ELF—several parsers in OS tool chain, which are all different. Can have two different Program Headers (PHDRs) because ld.so parses multiple PHDRs. The second PHDR can completely transform the executable. This is described in paper in the first issue of International Journal of PoC. Conclusions trusting computers not only about bugs! Bugs are part of a problem, but no by far all of it complex data formats means bugs no "chain of trust" in Babylon! (that is, with parser differentials) we need to squeeze complexity out of data until data stops being "code equivalent" Further information See and langsec.org. USENIX WOOT 2013 (Workshop on Offensive Technologies) for "weird machines" papers and videos.

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• Cannot open root device xvda1 or unknown-block(0,0)

  - by svoop

  I'm putting together a Dom0 and three DomU (all Gentoo) with kernel 3.5.7 and Xen 4.1.1. Each Dom has it's own md (md0 for Dom0, md1 for Dom1 etc). Dom0 works fine so far, however, I'm stuck trying to create DomUs. It appears the xvda1 device on DomU is not created or accessible: Parsing config file dom1 domainbuilder: detail: xc_dom_allocate: cmdline="root=/dev/xvda1 console=hvc0 root=/dev/xvda1 ro 3", features="(null)" domainbuilder: detail: xc_dom_kernel_mem: called domainbuilder: detail: xc_dom_boot_xen_init: ver 4.1, caps xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64 domainbuilder: detail: xc_dom_parse_image: called domainbuilder: detail: xc_dom_find_loader: trying multiboot-binary loader ... domainbuilder: detail: loader probe failed domainbuilder: detail: xc_dom_find_loader: trying Linux bzImage loader ... domainbuilder: detail: xc_dom_malloc : 10530 kB domainbuilder: detail: xc_dom_do_gunzip: unzip ok, 0x2f7a4f -> 0xa48888 domainbuilder: detail: loader probe OK xc: detail: elf_parse_binary: phdr: paddr=0x1000000 memsz=0x558000 xc: detail: elf_parse_binary: phdr: paddr=0x1558000 memsz=0x690e8 xc: detail: elf_parse_binary: phdr: paddr=0x15c2000 memsz=0x127c0 xc: detail: elf_parse_binary: phdr: paddr=0x15d5000 memsz=0x533000 xc: detail: elf_parse_binary: memory: 0x1000000 -> 0x1b08000 xc: detail: elf_xen_parse_note: GUEST_OS = "linux" xc: detail: elf_xen_parse_note: GUEST_VERSION = "2.6" xc: detail: elf_xen_parse_note: XEN_VERSION = "xen-3.0" xc: detail: elf_xen_parse_note: VIRT_BASE = 0xffffffff80000000 xc: detail: elf_xen_parse_note: ENTRY = 0xffffffff815d5210 xc: detail: elf_xen_parse_note: HYPERCALL_PAGE = 0xffffffff81001000 xc: detail: elf_xen_parse_note: FEATURES = "!writable_page_tables|pae_pgdir_above_4gb" xc: detail: elf_xen_parse_note: PAE_MODE = "yes" xc: detail: elf_xen_parse_note: LOADER = "generic" xc: detail: elf_xen_parse_note: unknown xen elf note (0xd) xc: detail: elf_xen_parse_note: SUSPEND_CANCEL = 0x1 xc: detail: elf_xen_parse_note: HV_START_LOW = 0xffff800000000000 xc: detail: elf_xen_parse_note: PADDR_OFFSET = 0x0 xc: detail: elf_xen_addr_calc_check: addresses: xc: detail: virt_base = 0xffffffff80000000 xc: detail: elf_paddr_offset = 0x0 xc: detail: virt_offset = 0xffffffff80000000 xc: detail: virt_kstart = 0xffffffff81000000 xc: detail: virt_kend = 0xffffffff81b08000 xc: detail: virt_entry = 0xffffffff815d5210 xc: detail: p2m_base = 0xffffffffffffffff domainbuilder: detail: xc_dom_parse_elf_kernel: xen-3.0-x86_64: 0xffffffff81000000 -> 0xffffffff81b08000 domainbuilder: detail: xc_dom_mem_init: mem 5000 MB, pages 0x138800 pages, 4k each domainbuilder: detail: xc_dom_mem_init: 0x138800 pages domainbuilder: detail: xc_dom_boot_mem_init: called domainbuilder: detail: x86_compat: guest xen-3.0-x86_64, address size 64 domainbuilder: detail: xc_dom_malloc : 10000 kB domainbuilder: detail: xc_dom_build_image: called domainbuilder: detail: xc_dom_alloc_segment: kernel : 0xffffffff81000000 -> 0xffffffff81b08000 (pfn 0x1000 + 0xb08 pages) domainbuilder: detail: xc_dom_pfn_to_ptr: domU mapping: pfn 0x1000+0xb08 at 0x7fdec9b85000 xc: detail: elf_load_binary: phdr 0 at 0x0x7fdec9b85000 -> 0x0x7fdeca0dd000 xc: detail: elf_load_binary: phdr 1 at 0x0x7fdeca0dd000 -> 0x0x7fdeca1460e8 xc: detail: elf_load_binary: phdr 2 at 0x0x7fdeca147000 -> 0x0x7fdeca1597c0 xc: detail: elf_load_binary: phdr 3 at 0x0x7fdeca15a000 -> 0x0x7fdeca1cd000 domainbuilder: detail: xc_dom_alloc_segment: phys2mach : 0xffffffff81b08000 -> 0xffffffff824cc000 (pfn 0x1b08 + 0x9c4 pages) domainbuilder: detail: xc_dom_pfn_to_ptr: domU mapping: pfn 0x1b08+0x9c4 at 0x7fdec91c1000 domainbuilder: detail: xc_dom_alloc_page : start info : 0xffffffff824cc000 (pfn 0x24cc) domainbuilder: detail: xc_dom_alloc_page : xenstore : 0xffffffff824cd000 (pfn 0x24cd) domainbuilder: detail: xc_dom_alloc_page : console : 0xffffffff824ce000 (pfn 0x24ce) domainbuilder: detail: nr_page_tables: 0x0000ffffffffffff/48: 0xffff000000000000 -> 0xffffffffffffffff, 1 table(s) domainbuilder: detail: nr_page_tables: 0x0000007fffffffff/39: 0xffffff8000000000 -> 0xffffffffffffffff, 1 table(s) domainbuilder: detail: nr_page_tables: 0x000000003fffffff/30: 0xffffffff80000000 -> 0xffffffffbfffffff, 1 table(s) domainbuilder: detail: nr_page_tables: 0x00000000001fffff/21: 0xffffffff80000000 -> 0xffffffff827fffff, 20 table(s) domainbuilder: detail: xc_dom_alloc_segment: page tables : 0xffffffff824cf000 -> 0xffffffff824e6000 (pfn 0x24cf + 0x17 pages) domainbuilder: detail: xc_dom_pfn_to_ptr: domU mapping: pfn 0x24cf+0x17 at 0x7fdece676000 domainbuilder: detail: xc_dom_alloc_page : boot stack : 0xffffffff824e6000 (pfn 0x24e6) domainbuilder: detail: xc_dom_build_image : virt_alloc_end : 0xffffffff824e7000 domainbuilder: detail: xc_dom_build_image : virt_pgtab_end : 0xffffffff82800000 domainbuilder: detail: xc_dom_boot_image: called domainbuilder: detail: arch_setup_bootearly: doing nothing domainbuilder: detail: xc_dom_compat_check: supported guest type: xen-3.0-x86_64 <= matches domainbuilder: detail: xc_dom_compat_check: supported guest type: xen-3.0-x86_32p domainbuilder: detail: xc_dom_compat_check: supported guest type: hvm-3.0-x86_32 domainbuilder: detail: xc_dom_compat_check: supported guest type: hvm-3.0-x86_32p domainbuilder: detail: xc_dom_compat_check: supported guest type: hvm-3.0-x86_64 domainbuilder: detail: xc_dom_update_guest_p2m: dst 64bit, pages 0x138800 domainbuilder: detail: clear_page: pfn 0x24ce, mfn 0x37ddee domainbuilder: detail: clear_page: pfn 0x24cd, mfn 0x37ddef domainbuilder: detail: xc_dom_pfn_to_ptr: domU mapping: pfn 0x24cc+0x1 at 0x7fdece675000 domainbuilder: detail: start_info_x86_64: called domainbuilder: detail: setup_hypercall_page: vaddr=0xffffffff81001000 pfn=0x1001 domainbuilder: detail: domain builder memory footprint domainbuilder: detail: allocated domainbuilder: detail: malloc : 20658 kB domainbuilder: detail: anon mmap : 0 bytes domainbuilder: detail: mapped domainbuilder: detail: file mmap : 0 bytes domainbuilder: detail: domU mmap : 21392 kB domainbuilder: detail: arch_setup_bootlate: shared_info: pfn 0x0, mfn 0xbaa6f domainbuilder: detail: shared_info_x86_64: called domainbuilder: detail: vcpu_x86_64: called domainbuilder: detail: vcpu_x86_64: cr3: pfn 0x24cf mfn 0x37dded domainbuilder: detail: launch_vm: called, ctxt=0x7fff224e4ea0 domainbuilder: detail: xc_dom_release: called Daemon running with PID 4639 [ 0.000000] Initializing cgroup subsys cpuset [ 0.000000] Initializing cgroup subsys cpu [ 0.000000] Linux version 3.5.7-gentoo (root@majordomo) (gcc version 4.5.4 (Gentoo 4.5.4 p1.0, pie-0.4.7) ) #1 SMP Tue Nov 20 10:49:51 CET 2012 [ 0.000000] Command line: root=/dev/xvda1 console=hvc0 root=/dev/xvda1 ro 3 [ 0.000000] ACPI in unprivileged domain disabled [ 0.000000] e820: BIOS-provided physical RAM map: [ 0.000000] Xen: [mem 0x0000000000000000-0x000000000009ffff] usable [ 0.000000] Xen: [mem 0x00000000000a0000-0x00000000000fffff] reserved [ 0.000000] Xen: [mem 0x0000000000100000-0x0000000138ffffff] usable [ 0.000000] NX (Execute Disable) protection: active [ 0.000000] MPS support code is not built-in. [ 0.000000] Using acpi=off or acpi=noirq or pci=noacpi may have problem [ 0.000000] DMI not present or invalid. [ 0.000000] No AGP bridge found [ 0.000000] e820: last_pfn = 0x139000 max_arch_pfn = 0x400000000 [ 0.000000] e820: last_pfn = 0x100000 max_arch_pfn = 0x400000000 [ 0.000000] init_memory_mapping: [mem 0x00000000-0xffffffff] [ 0.000000] init_memory_mapping: [mem 0x100000000-0x138ffffff] [ 0.000000] NUMA turned off [ 0.000000] Faking a node at [mem 0x0000000000000000-0x0000000138ffffff] [ 0.000000] Initmem setup node 0 [mem 0x00000000-0x138ffffff] [ 0.000000] NODE_DATA [mem 0x1387fc000-0x1387fffff] [ 0.000000] Zone ranges: [ 0.000000] DMA [mem 0x00010000-0x00ffffff] [ 0.000000] DMA32 [mem 0x01000000-0xffffffff] [ 0.000000] Normal [mem 0x100000000-0x138ffffff] [ 0.000000] Movable zone start for each node [ 0.000000] Early memory node ranges [ 0.000000] node 0: [mem 0x00010000-0x0009ffff] [ 0.000000] node 0: [mem 0x00100000-0x138ffffff] [ 0.000000] SMP: Allowing 1 CPUs, 0 hotplug CPUs [ 0.000000] No local APIC present [ 0.000000] APIC: disable apic facility [ 0.000000] APIC: switched to apic NOOP [ 0.000000] e820: cannot find a gap in the 32bit address range [ 0.000000] e820: PCI devices with unassigned 32bit BARs may break! [ 0.000000] e820: [mem 0x139100000-0x1394fffff] available for PCI devices [ 0.000000] Booting paravirtualized kernel on Xen [ 0.000000] Xen version: 4.1.1 (preserve-AD) [ 0.000000] setup_percpu: NR_CPUS:64 nr_cpumask_bits:64 nr_cpu_ids:1 nr_node_ids:1 [ 0.000000] PERCPU: Embedded 26 pages/cpu @ffff880138400000 s75712 r8192 d22592 u2097152 [ 0.000000] Built 1 zonelists in Node order, mobility grouping on. Total pages: 1259871 [ 0.000000] Policy zone: Normal [ 0.000000] Kernel command line: root=/dev/xvda1 console=hvc0 root=/dev/xvda1 ro 3 [ 0.000000] PID hash table entries: 4096 (order: 3, 32768 bytes) [ 0.000000] __ex_table already sorted, skipping sort [ 0.000000] Checking aperture... [ 0.000000] No AGP bridge found [ 0.000000] Memory: 4943980k/5128192k available (3937k kernel code, 448k absent, 183764k reserved, 1951k data, 524k init) [ 0.000000] SLUB: Genslabs=15, HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1 [ 0.000000] Hierarchical RCU implementation. [ 0.000000] NR_IRQS:4352 nr_irqs:256 16 [ 0.000000] Console: colour dummy device 80x25 [ 0.000000] console [tty0] enabled [ 0.000000] console [hvc0] enabled [ 0.000000] installing Xen timer for CPU 0 [ 0.000000] Detected 3411.602 MHz processor. [ 0.000999] Calibrating delay loop (skipped), value calculated using timer frequency.. 6823.20 BogoMIPS (lpj=3411602) [ 0.000999] pid_max: default: 32768 minimum: 301 [ 0.000999] Security Framework initialized [ 0.001355] Dentry cache hash table entries: 1048576 (order: 11, 8388608 bytes) [ 0.002974] Inode-cache hash table entries: 524288 (order: 10, 4194304 bytes) [ 0.003441] Mount-cache hash table entries: 256 [ 0.003595] Initializing cgroup subsys cpuacct [ 0.003599] Initializing cgroup subsys freezer [ 0.003637] ENERGY_PERF_BIAS: Set to 'normal', was 'performance' [ 0.003637] ENERGY_PERF_BIAS: View and update with x86_energy_perf_policy(8) [ 0.003643] CPU: Physical Processor ID: 0 [ 0.003645] CPU: Processor Core ID: 0 [ 0.003702] SMP alternatives: switching to UP code [ 0.011791] Freeing SMP alternatives: 12k freed [ 0.011835] Performance Events: unsupported p6 CPU model 42 no PMU driver, software events only. [ 0.011886] Brought up 1 CPUs [ 0.011998] Grant tables using version 2 layout. [ 0.012009] Grant table initialized [ 0.012034] NET: Registered protocol family 16 [ 0.012328] PCI: setting up Xen PCI frontend stub [ 0.015089] bio: create slab <bio-0> at 0 [ 0.015158] ACPI: Interpreter disabled. [ 0.015180] xen/balloon: Initialising balloon driver. [ 0.015180] xen-balloon: Initialising balloon driver. [ 0.015180] vgaarb: loaded [ 0.016126] SCSI subsystem initialized [ 0.016314] PCI: System does not support PCI [ 0.016320] PCI: System does not support PCI [ 0.016435] NetLabel: Initializing [ 0.016438] NetLabel: domain hash size = 128 [ 0.016440] NetLabel: protocols = UNLABELED CIPSOv4 [ 0.016447] NetLabel: unlabeled traffic allowed by default [ 0.016475] Switching to clocksource xen [ 0.017434] pnp: PnP ACPI: disabled [ 0.017501] NET: Registered protocol family 2 [ 0.017864] IP route cache hash table entries: 262144 (order: 9, 2097152 bytes) [ 0.019322] TCP established hash table entries: 524288 (order: 11, 8388608 bytes) [ 0.020376] TCP bind hash table entries: 65536 (order: 8, 1048576 bytes) [ 0.020497] TCP: Hash tables configured (established 524288 bind 65536) [ 0.020500] TCP: reno registered [ 0.020525] UDP hash table entries: 4096 (order: 5, 131072 bytes) [ 0.020564] UDP-Lite hash table entries: 4096 (order: 5, 131072 bytes) [ 0.020624] NET: Registered protocol family 1 [ 0.020658] PCI-DMA: Using software bounce buffering for IO (SWIOTLB) [ 0.020662] software IO TLB [mem 0xfb632000-0xff631fff] (64MB) mapped at [ffff8800fb632000-ffff8800ff631fff] [ 0.020750] platform rtc_cmos: registered platform RTC device (no PNP device found) [ 0.021378] HugeTLB registered 2 MB page size, pre-allocated 0 pages [ 0.023378] msgmni has been set to 9656 [ 0.023544] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 253) [ 0.023549] io scheduler noop registered [ 0.023551] io scheduler deadline registered [ 0.023580] io scheduler cfq registered (default) [ 0.023650] pci_hotplug: PCI Hot Plug PCI Core version: 0.5 [ 0.023845] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled [ 0.024082] Non-volatile memory driver v1.3 [ 0.024085] Linux agpgart interface v0.103 [ 0.024207] Event-channel device installed. [ 0.024265] [drm] Initialized drm 1.1.0 20060810 [ 0.024268] [drm:i915_init] *ERROR* drm/i915 can't work without intel_agp module! [ 0.025145] brd: module loaded [ 0.025565] loop: module loaded [ 0.045646] Initialising Xen virtual ethernet driver. [ 0.198264] i8042: PNP: No PS/2 controller found. Probing ports directly. [ 0.199096] i8042: No controller found [ 0.199139] mousedev: PS/2 mouse device common for all mice [ 0.259303] rtc_cmos rtc_cmos: rtc core: registered rtc_cmos as rtc0 [ 0.259353] rtc_cmos: probe of rtc_cmos failed with error -38 [ 0.259440] md: raid1 personality registered for level 1 [ 0.259542] nf_conntrack version 0.5.0 (16384 buckets, 65536 max) [ 0.259732] ip_tables: (C) 2000-2006 Netfilter Core Team [ 0.259747] TCP: cubic registered [ 0.259886] NET: Registered protocol family 10 [ 0.260031] ip6_tables: (C) 2000-2006 Netfilter Core Team [ 0.260070] sit: IPv6 over IPv4 tunneling driver [ 0.260194] NET: Registered protocol family 17 [ 0.260213] Bridge firewalling registered [ 5.360075] XENBUS: Waiting for devices to initialise: 25s...20s...15s...10s...5s...0s...235s...230s...225s...220s...215s...210s...205s...200s...195s...190s...185s...180s...175s...170s...165s...160s...155s...150s...145s...140s...135s...130s...125s...120s...115s...110s...105s...100s...95s...90s...85s...80s...75s...70s...65s...60s...55s...50s...45s...40s...35s...30s...25s...20s...15s...10s...5s...0s... [ 270.360180] XENBUS: Timeout connecting to device: device/vbd/51713 (local state 3, remote state 1) [ 270.360273] md: Waiting for all devices to be available before autodetect [ 270.360277] md: If you don't use raid, use raid=noautodetect [ 270.360388] md: Autodetecting RAID arrays. [ 270.360392] md: Scanned 0 and added 0 devices. [ 270.360394] md: autorun ... [ 270.360395] md: ... autorun DONE. [ 270.360431] VFS: Cannot open root device "xvda1" or unknown-block(0,0): error -6 [ 270.360435] Please append a correct "root=" boot option; here are the available partitions: [ 270.360440] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0) [ 270.360444] Pid: 1, comm: swapper/0 Not tainted 3.5.7-gentoo #1 [ 270.360446] Call Trace: [ 270.360454] [<ffffffff813d2205>] ? panic+0xbe/0x1c5 [ 270.360459] [<ffffffff813d2358>] ? printk+0x4c/0x51 [ 270.360464] [<ffffffff815d5fb7>] ? mount_block_root+0x24f/0x26d [ 270.360469] [<ffffffff815d62b6>] ? prepare_namespace+0x168/0x192 [ 270.360474] [<ffffffff815d5ca7>] ? kernel_init+0x1b0/0x1c2 [ 270.360477] [<ffffffff815d5500>] ? loglevel+0x34/0x34 [ 270.360482] [<ffffffff813d5a64>] ? kernel_thread_helper+0x4/0x10 [ 270.360486] [<ffffffff813d4038>] ? retint_restore_args+0x5/0x6 [ 270.360490] [<ffffffff813d5a60>] ? gs_change+0x13/0x13 The config: name = "dom1" bootloader = "/usr/bin/pygrub" root = "/dev/xvda1 ro" extra = "3" # runlevel memory = 5000 disk = [ 'phy:/dev/md1,xvda1,w' ] # vif = [ 'ip=..., vifname=veth1' ] # none for now Here are some details on the Dom0 kernel (grepping for "xen"): CONFIG_XEN=y CONFIG_XEN_DOM0=y CONFIG_XEN_PRIVILEGED_GUEST=y CONFIG_XEN_PVHVM=y CONFIG_XEN_MAX_DOMAIN_MEMORY=500 CONFIG_XEN_SAVE_RESTORE=y CONFIG_PCI_XEN=y CONFIG_XEN_PCIDEV_FRONTEND=y # CONFIG_XEN_BLKDEV_FRONTEND is not set CONFIG_XEN_BLKDEV_BACKEND=y # CONFIG_XEN_NETDEV_FRONTEND is not set CONFIG_XEN_NETDEV_BACKEND=y CONFIG_INPUT_XEN_KBDDEV_FRONTEND=y CONFIG_HVC_XEN=y CONFIG_HVC_XEN_FRONTEND=y # CONFIG_XEN_WDT is not set # CONFIG_XEN_FBDEV_FRONTEND is not set # Xen driver support CONFIG_XEN_BALLOON=y # CONFIG_XEN_SELFBALLOONING is not set CONFIG_XEN_SCRUB_PAGES=y CONFIG_XEN_DEV_EVTCHN=y CONFIG_XEN_BACKEND=y CONFIG_XENFS=y CONFIG_XEN_COMPAT_XENFS=y CONFIG_XEN_SYS_HYPERVISOR=y CONFIG_XEN_XENBUS_FRONTEND=y CONFIG_XEN_GNTDEV=m CONFIG_XEN_GRANT_DEV_ALLOC=m CONFIG_SWIOTLB_XEN=y CONFIG_XEN_TMEM=y CONFIG_XEN_PCIDEV_BACKEND=m CONFIG_XEN_PRIVCMD=y CONFIG_XEN_ACPI_PROCESSOR=m And the DomU kernel (grepping for "xen"): CONFIG_XEN=y CONFIG_XEN_DOM0=y CONFIG_XEN_PRIVILEGED_GUEST=y CONFIG_XEN_PVHVM=y CONFIG_XEN_MAX_DOMAIN_MEMORY=500 CONFIG_XEN_SAVE_RESTORE=y CONFIG_PCI_XEN=y CONFIG_XEN_PCIDEV_FRONTEND=y CONFIG_XEN_BLKDEV_FRONTEND=y CONFIG_XEN_NETDEV_FRONTEND=y CONFIG_INPUT_XEN_KBDDEV_FRONTEND=y CONFIG_HVC_XEN=y CONFIG_HVC_XEN_FRONTEND=y # CONFIG_XEN_WDT is not set # CONFIG_XEN_FBDEV_FRONTEND is not set # Xen driver support CONFIG_XEN_BALLOON=y # CONFIG_XEN_SELFBALLOONING is not set CONFIG_XEN_SCRUB_PAGES=y CONFIG_XEN_DEV_EVTCHN=y # CONFIG_XEN_BACKEND is not set CONFIG_XENFS=y CONFIG_XEN_COMPAT_XENFS=y CONFIG_XEN_SYS_HYPERVISOR=y CONFIG_XEN_XENBUS_FRONTEND=y CONFIG_XEN_GNTDEV=m CONFIG_XEN_GRANT_DEV_ALLOC=m CONFIG_SWIOTLB_XEN=y CONFIG_XEN_TMEM=y CONFIG_XEN_PRIVCMD=y CONFIG_XEN_ACPI_PROCESSOR=m Any ideas what I'm doing wrong here? Thanks a lot!

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• What is the fastest cyclic synchronization in Java (ExecutorService vs. CyclicBarrier vs. X)?

  - by Alex Dunlop

  Which Java synchronization construct is likely to provide the best performance for a concurrent, iterative processing scenario with a fixed number of threads like the one outlined below? After experimenting on my own for a while (using ExecutorService and CyclicBarrier) and being somewhat surprised by the results, I would be grateful for some expert advice and maybe some new ideas. Existing questions here do not seem to focus primarily on performance, hence this new one. Thanks in advance! The core of the app is a simple iterative data processing algorithm, parallelized to the spread the computational load across 8 cores on a Mac Pro, running OS X 10.6 and Java 1.6.0_07. The data to be processed is split into 8 blocks and each block is fed to a Runnable to be executed by one of a fixed number of threads. Parallelizing the algorithm was fairly straightforward, and it functionally works as desired, but its performance is not yet what I think it could be. The app seems to spend a lot of time in system calls synchronizing, so after some profiling I wonder whether I selected the most appropriate synchronization mechanism(s). A key requirement of the algorithm is that it needs to proceed in stages, so the threads need to sync up at the end of each stage. The main thread prepares the work (very low overhead), passes it to the threads, lets them work on it, then proceeds when all threads are done, rearranges the work (again very low overhead) and repeats the cycle. The machine is dedicated to this task, Garbage Collection is minimized by using per-thread pools of pre-allocated items, and the number of threads can be fixed (no incoming requests or the like, just one thread per CPU core). V1 - ExecutorService My first implementation used an ExecutorService with 8 worker threads. The program creates 8 tasks holding the work and then lets them work on it, roughly like this: // create one thread per CPU executorService = Executors.newFixedThreadPool( 8 ); ... // now process data in cycles while( ...) { // package data into 8 work items ... // create one Callable task per work item ... // submit the Callables to the worker threads executorService.invokeAll( taskList ); } This works well functionally (it does what it should), and for very large work items indeed all 8 CPUs become highly loaded, as much as the processing algorithm would be expected to allow (some work items will finish faster than others, then idle). However, as the work items become smaller (and this is not really under the program's control), the user CPU load shrinks dramatically: blocksize | system | user | cycles/sec 256k 1.8% 85% 1.30 64k 2.5% 77% 5.6 16k 4% 64% 22.5 4096 8% 56% 86 1024 13% 38% 227 256 17% 19% 420 64 19% 17% 948 16 19% 13% 1626 Legend: - block size = size of the work item (= computational steps) - system = system load, as shown in OS X Activity Monitor (red bar) - user = user load, as shown in OS X Activity Monitor (green bar) - cycles/sec = iterations through the main while loop, more is better The primary area of concern here is the high percentage of time spent in the system, which appears to be driven by thread synchronization calls. As expected, for smaller work items, ExecutorService.invokeAll() will require relatively more effort to sync up the threads versus the amount of work being performed in each thread. But since ExecutorService is more generic than it would need to be for this use case (it can queue tasks for threads if there are more tasks than cores), I though maybe there would be a leaner synchronization construct. V2 - CyclicBarrier The next implementation used a CyclicBarrier to sync up the threads before receiving work and after completing it, roughly as follows: main() { // create the barrier barrier = new CyclicBarrier( 8 + 1 ); // create Runable for thread, tell it about the barrier Runnable task = new WorkerThreadRunnable( barrier ); // start the threads for( int i = 0; i < 8; i++ ) { // create one thread per core new Thread( task ).start(); } while( ... ) { // tell threads about the work ... // N threads + this will call await(), then system proceeds barrier.await(); // ... now worker threads work on the work... // wait for worker threads to finish barrier.await(); } } class WorkerThreadRunnable implements Runnable { CyclicBarrier barrier; WorkerThreadRunnable( CyclicBarrier barrier ) { this.barrier = barrier; } public void run() { while( true ) { // wait for work barrier.await(); // do the work ... // wait for everyone else to finish barrier.await(); } } } Again, this works well functionally (it does what it should), and for very large work items indeed all 8 CPUs become highly loaded, as before. However, as the work items become smaller, the load still shrinks dramatically: blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.7% 78% 6.1 16k 5.5% 52% 25 4096 9% 29% 64 1024 11% 15% 117 256 12% 8% 169 64 12% 6.5% 285 16 12% 6% 377 For large work items, synchronization is negligible and the performance is identical to V1. But unexpectedly, the results of the (highly specialized) CyclicBarrier seem MUCH WORSE than those for the (generic) ExecutorService: throughput (cycles/sec) is only about 1/4th of V1. A preliminary conclusion would be that even though this seems to be the advertised ideal use case for CyclicBarrier, it performs much worse than the generic ExecutorService. V3 - Wait/Notify + CyclicBarrier It seemed worth a try to replace the first cyclic barrier await() with a simple wait/notify mechanism: main() { // create the barrier // create Runable for thread, tell it about the barrier // start the threads while( ... ) { // tell threads about the work // for each: workerThreadRunnable.setWorkItem( ... ); // ... now worker threads work on the work... // wait for worker threads to finish barrier.await(); } } class WorkerThreadRunnable implements Runnable { CyclicBarrier barrier; @NotNull volatile private Callable<Integer> workItem; WorkerThreadRunnable( CyclicBarrier barrier ) { this.barrier = barrier; this.workItem = NO_WORK; } final protected void setWorkItem( @NotNull final Callable<Integer> callable ) { synchronized( this ) { workItem = callable; notify(); } } public void run() { while( true ) { // wait for work while( true ) { synchronized( this ) { if( workItem != NO_WORK ) break; try { wait(); } catch( InterruptedException e ) { e.printStackTrace(); } } } // do the work ... // wait for everyone else to finish barrier.await(); } } } Again, this works well functionally (it does what it should). blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.4% 80% 6.3 16k 4.6% 60% 30.1 4096 8.6% 41% 98.5 1024 12% 23% 202 256 14% 11.6% 299 64 14% 10.0% 518 16 14.8% 8.7% 679 The throughput for small work items is still much worse than that of the ExecutorService, but about 2x that of the CyclicBarrier. Eliminating one CyclicBarrier eliminates half of the gap. V4 - Busy wait instead of wait/notify Since this app is the primary one running on the system and the cores idle anyway if they're not busy with a work item, why not try a busy wait for work items in each thread, even if that spins the CPU needlessly. The worker thread code changes as follows: class WorkerThreadRunnable implements Runnable { // as before final protected void setWorkItem( @NotNull final Callable<Integer> callable ) { workItem = callable; } public void run() { while( true ) { // busy-wait for work while( true ) { if( workItem != NO_WORK ) break; } // do the work ... // wait for everyone else to finish barrier.await(); } } } Also works well functionally (it does what it should). blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.2% 81% 6.3 16k 4.2% 62% 33 4096 7.5% 40% 107 1024 10.4% 23% 210 256 12.0% 12.0% 310 64 11.9% 10.2% 550 16 12.2% 8.6% 741 For small work items, this increases throughput by a further 10% over the CyclicBarrier + wait/notify variant, which is not insignificant. But it is still much lower-throughput than V1 with the ExecutorService. V5 - ? So what is the best synchronization mechanism for such a (presumably not uncommon) problem? I am weary of writing my own sync mechanism to completely replace ExecutorService (assuming that it is too generic and there has to be something that can still be taken out to make it more efficient). It is not my area of expertise and I'm concerned that I'd spend a lot of time debugging it (since I'm not even sure my wait/notify and busy wait variants are correct) for uncertain gain. Any advice would be greatly appreciated.

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• Communicating between C# application and Android app via bluetooth

  - by Akki

  The android application acts as a server in this case. I have a main activity which creates a Thread to handle serverSocket and a different thread to handle the socket connection. I am using a uuid common to C# and android. I am using 32feet bluetooth library for C#. The errors i am facing are 1) My logcat shows this debug log Error while doing socket.connect()1 java.io.IOException: File descriptor in bad state Message: File descriptor in bad state Localized Message: File descriptor in bad state Received : Testing Connection Count of Thread is : 1 2) When i try to send something via C# app the second time, this exception is thrown: A first chance exception of type 'System.InvalidOperationException' occurred in System.dll System.InvalidOperationException: BeginConnect cannot be called while another asynchronous operation is in progress on the same Socket. at System.Net.Sockets.Socket.DoBeginConnect(EndPoint endPointSnapshot, SocketAddress socketAddress, LazyAsyncResult asyncResult) at System.Net.Sockets.Socket.BeginConnect(EndPoint remoteEP, AsyncCallback callback, Object state) at InTheHand.Net.Bluetooth.Msft.SocketBluetoothClient.BeginConnect(BluetoothEndPoint remoteEP, AsyncCallback requestCallback, Object state) at InTheHand.Net.Sockets.BluetoothClient.BeginConnect(BluetoothEndPoint remoteEP, AsyncCallback requestCallback, Object state) at InTheHand.Net.Sockets.BluetoothClient.BeginConnect(BluetoothAddress address, Guid service, AsyncCallback requestCallback, Object state) at BTSyncClient.Form1.connect() in c:\users\----\documents\visual studio 2010\Projects\TestClient\TestClient\Form1.cs:line 154 I only know android application programming and i designed the C# by learning bit and pieces. FYI, My android phone is galaxy s with ICS running on it.Please point out my mistakes.. Source codes : C# Code using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Threading; using System.Net.Sockets; using InTheHand.Net.Bluetooth; using InTheHand.Windows.Forms; using InTheHand.Net.Sockets; using InTheHand.Net; namespace BTSyncClient { public partial class Form1 : Form { BluetoothClient myself; BluetoothDeviceInfo bTServerDevice; private Guid uuid = Guid.Parse("00001101-0000-1000-8000-00805F9B34FB"); bool isConnected; public Form1() { InitializeComponent(); if (BluetoothRadio.IsSupported) { myself = new BluetoothClient(); } } private void Form1_Load(object sender, EventArgs e) { } private void button1_Click(object sender, EventArgs e) { connect(); } private void Form1_FormClosing(object sender, FormClosingEventArgs e) { try { myself.GetStream().Close(); myself.Dispose(); } catch (Exception ex) { Console.Out.WriteLine(ex); } } private void button2_Click(object sender, EventArgs e) { SelectBluetoothDeviceDialog dialog = new SelectBluetoothDeviceDialog(); DialogResult result = dialog.ShowDialog(this); if(result.Equals(DialogResult.OK)){ bTServerDevice = dialog.SelectedDevice; } } private void callback(IAsyncResult ar) { String msg = (String)ar.AsyncState; if (ar.IsCompleted) { isConnected = myself.Connected; if (myself.Connected) { UTF8Encoding encoder = new UTF8Encoding(); NetworkStream stream = myself.GetStream(); if (!stream.CanWrite) { MessageBox.Show("Stream is not Writable"); } System.IO.StreamWriter mywriter = new System.IO.StreamWriter(stream, Encoding.UTF8); mywriter.WriteLine(msg); mywriter.Flush(); } else MessageBox.Show("Damn thing isnt connected"); } } private void connect() { try { if (bTServerDevice != null) { myself.BeginConnect(bTServerDevice.DeviceAddress, uuid, new AsyncCallback(callback) , message.Text); } } catch (Exception e) { Console.Out.WriteLine(e); } } } } Server Thread import java.io.IOException; import java.util.UUID; import android.bluetooth.BluetoothAdapter; import android.bluetooth.BluetoothServerSocket; import android.bluetooth.BluetoothSocket; import android.util.Log; public class ServerSocketThread extends Thread { private static final String TAG = "TestApp"; private BluetoothAdapter btAdapter; private BluetoothServerSocket serverSocket; private boolean stopMe; private static final UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); //private static final UUID uuid = UUID.fromString("6e58c9d5-b0b6-4009-ad9b-fd9481aef9b3"); private static final String SERVICE_NAME = "TestService"; public ServerSocketThread() { stopMe = false; btAdapter = BluetoothAdapter.getDefaultAdapter(); try { serverSocket = btAdapter.listenUsingRfcommWithServiceRecord(SERVICE_NAME, uuid); } catch (IOException e) { Log.d(TAG,e.toString()); } } public void signalStop(){ stopMe = true; } public void run(){ Log.d(TAG,"In ServerThread"); BluetoothSocket socket = null; while(!stopMe){ try { socket = serverSocket.accept(); } catch (IOException e) { break; } if(socket != null){ AcceptThread newClientConnection = new AcceptThread(socket); newClientConnection.start(); } } Log.d(TAG,"Server Thread now dead"); } // Will cancel the listening socket and cause the thread to finish public void cancel(){ try { serverSocket.close(); } catch (IOException e) { } } } Accept Thread import java.io.IOException; import java.io.InputStream; import java.util.Scanner; import android.bluetooth.BluetoothSocket; import android.util.Log; public class AcceptThread extends Thread { private BluetoothSocket socket; private String TAG = "TestApp"; static int count = 0; public AcceptThread(BluetoothSocket Socket) { socket = Socket; } volatile boolean isError; String output; String error; public void run() { Log.d(TAG, "AcceptThread Started"); isError = false; try { socket.connect(); } catch (IOException e) { Log.d(TAG,"Error while doing socket.connect()"+ ++count); Log.d(TAG, e.toString()); Log.d(TAG,"Message: "+e.getLocalizedMessage()); Log.d(TAG,"Localized Message: "+e.getMessage()); isError = true; } InputStream in = null; try { in = socket.getInputStream(); } catch (IOException e) { Log.d(TAG,"Error while doing socket.getInputStream()"); Log.d(TAG, e.toString()); Log.d(TAG,"Message: "+e.getLocalizedMessage()); Log.d(TAG,"Localized Message: "+e.getMessage()); isError = true; } Scanner istream = new Scanner(in); if (istream.hasNextLine()) { Log.d(TAG, "Received : "+istream.nextLine()); Log.d(TAG,"Count of Thread is : " + count); } istream.close(); try { in.close(); } catch (IOException e) { Log.d(TAG,"Error while doing in.close()"); Log.d(TAG, e.toString()); Log.d(TAG,"Message: "+e.getLocalizedMessage()); Log.d(TAG,"Localized Message: "+e.getMessage()); isError = true; } try { socket.close(); } catch (IOException e) { Log.d(TAG,"Error while doing socket.close()"); Log.d(TAG, e.toString()); Log.d(TAG,"Message: "+e.getLocalizedMessage()); Log.d(TAG,"Localized Message: "+e.getMessage()); isError = true; } } }

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• Reading a child process's /proc/pid/mem file from the parent

  - by Amittai Aviram

  In the program below, I am trying to cause the following to happen: Process A assigns a value to a stack variable a. Process A (parent) creates process B (child) with PID child_pid. Process B calls function func1, passing a pointer to a. Process B changes the value of variable a through the pointer. Process B opens its /proc/self/mem file, seeks to the page containing a, and prints the new value of a. Process A (at the same time) opens /proc/child_pid/mem, seeks to the right page, and prints the new value of a. The problem is that, in step 6, the parent only sees the old value of a in /proc/child_pid/mem, while the child can indeed see the new value in its /proc/self/mem. Why is this the case? Is there any way that I can get the parent to to see the child's changes to its address space through the /proc filesystem? #include <fcntl.h> #include <stdbool.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <sys/stat.h> #include <sys/wait.h> #include <unistd.h> #define PAGE_SIZE 0x1000 #define LOG_PAGE_SIZE 0xc #define PAGE_ROUND_DOWN(v) ((v) & (~(PAGE_SIZE - 1))) #define PAGE_ROUND_UP(v) (((v) + PAGE_SIZE - 1) & (~(PAGE_SIZE - 1))) #define OFFSET_IN_PAGE(v) ((v) & (PAGE_SIZE - 1)) # if defined ARCH && ARCH == 32 #define BP "ebp" #define SP "esp" #else #define BP "rbp" #define SP "rsp" #endif typedef struct arg_t { int a; } arg_t; void func1(void * data) { arg_t * arg_ptr = (arg_t *)data; printf("func1: old value: %d\n", arg_ptr->a); arg_ptr->a = 53; printf("func1: address: %p\n", &arg_ptr->a); printf("func1: new value: %d\n", arg_ptr->a); } void expore_proc_mem(void (*fn)(void *), void * data) { off_t frame_pointer, stack_start; char buffer[PAGE_SIZE]; const char * path = "/proc/self/mem"; int child_pid, status; int parent_to_child[2]; int child_to_parent[2]; arg_t * arg_ptr; off_t child_offset; asm volatile ("mov %%"BP", %0" : "=m" (frame_pointer)); stack_start = PAGE_ROUND_DOWN(frame_pointer); printf("Stack_start: %lx\n", (unsigned long)stack_start); arg_ptr = (arg_t *)data; child_offset = OFFSET_IN_PAGE((off_t)&arg_ptr->a); printf("Address of arg_ptr->a: %p\n", &arg_ptr->a); pipe(parent_to_child); pipe(child_to_parent); bool msg; int child_mem_fd; char child_path[0x20]; child_pid = fork(); if (child_pid == -1) { perror("fork"); exit(EXIT_FAILURE); } if (!child_pid) { close(child_to_parent[0]); close(parent_to_child[1]); printf("CHILD (pid %d, parent pid %d).\n", getpid(), getppid()); fn(data); msg = true; write(child_to_parent[1], &msg, 1); child_mem_fd = open("/proc/self/mem", O_RDONLY); if (child_mem_fd == -1) { perror("open (child)"); exit(EXIT_FAILURE); } printf("CHILD: child_mem_fd: %d\n", child_mem_fd); if (lseek(child_mem_fd, stack_start, SEEK_SET) == (off_t)-1) { perror("lseek"); exit(EXIT_FAILURE); } if (read(child_mem_fd, buffer, sizeof(buffer)) != sizeof(buffer)) { perror("read"); exit(EXIT_FAILURE); } printf("CHILD: new value %d\n", *(int *)(buffer + child_offset)); read(parent_to_child[0], &msg, 1); exit(EXIT_SUCCESS); } else { printf("PARENT (pid %d, child pid %d)\n", getpid(), child_pid); printf("PARENT: child_offset: %lx\n", child_offset); read(child_to_parent[0], &msg, 1); printf("PARENT: message from child: %d\n", msg); snprintf(child_path, 0x20, "/proc/%d/mem", child_pid); printf("PARENT: child_path: %s\n", child_path); child_mem_fd = open(path, O_RDONLY); if (child_mem_fd == -1) { perror("open (child)"); exit(EXIT_FAILURE); } printf("PARENT: child_mem_fd: %d\n", child_mem_fd); if (lseek(child_mem_fd, stack_start, SEEK_SET) == (off_t)-1) { perror("lseek"); exit(EXIT_FAILURE); } if (read(child_mem_fd, buffer, sizeof(buffer)) != sizeof(buffer)) { perror("read"); exit(EXIT_FAILURE); } printf("PARENT: new value %d\n", *(int *)(buffer + child_offset)); close(child_mem_fd); printf("ENDING CHILD PROCESS.\n"); write(parent_to_child[1], &msg, 1); if (waitpid(child_pid, &status, 0) == -1) { perror("waitpid"); exit(EXIT_FAILURE); } } } int main(void) { arg_t arg; arg.a = 42; printf("In main: address of arg.a: %p\n", &arg.a); explore_proc_mem(&func1, &arg.a); return EXIT_SUCCESS; } This program produces the output below. Notice that the value of a (boldfaced) differs between parent's and child's reading of the /proc/child_pid/mem file. In main: address of arg.a: 0x7ffffe1964f0 Stack_start: 7ffffe196000 Address of arg_ptr-a: 0x7ffffe1964f0 PARENT (pid 20376, child pid 20377) PARENT: child_offset: 4f0 CHILD (pid 20377, parent pid 20376). func1: old value: 42 func1: address: 0x7ffffe1964f0 func1: new value: 53 PARENT: message from child: 1 CHILD: child_mem_fd: 4 PARENT: child_path: /proc/20377/mem CHILD: new value 53 PARENT: child_mem_fd: 7 PARENT: new value 42 ENDING CHILD PROCESS.

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• Probelm with String.split() in java

  - by Matt

  What I am trying to do is read a .java file, and pick out all of the identifiers and store them in a list. My problem is with the .split() method. If you run this code the way it is, you will get ArrayOutOfBounds, but if you change the delimiter from "." to anything else, the code works. But I need to lines parsed by "." so is there another way I could accomplish this? import java.io.BufferedReader; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.IOException; import java.util.*; public class MyHash { private static String[] reserved = new String[100]; private static List list = new LinkedList(); private static List list2 = new LinkedList(); public static void main (String args[]){ Hashtable hashtable = new Hashtable(997); makeReserved(); readFile(); String line; ListIterator itr = list.listIterator(); int listIndex = 0; while (listIndex < list.size()) { if (itr.hasNext()){ line = itr.next().toString(); //PROBLEM IS HERE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! String[] words = line.split("."); //CHANGE THIS AND IT WILL WORK System.out.println(words[0]); //TESTING TO SEE IF IT WORKED } listIndex++; } } public static void readFile() { String text; String[] words; BufferedReader in = null; try { in = new BufferedReader(new FileReader("MyHash.java")); //NAME OF INPUT FILE } catch (FileNotFoundException ex) { Logger.getLogger(MyHash.class.getName()).log(Level.SEVERE, null, ex); } try { while ((text = in.readLine()) != null){ text = text.trim(); words = text.split("\\s+"); for (int i = 0; i < words.length; i++){ list.add(words[i]); } for (int j = 0; j < reserved.length; j++){ if (list.contains(reserved[j])){ list.remove(reserved[j]); } } } } catch (IOException ex) { Logger.getLogger(MyHash.class.getName()).log(Level.SEVERE, null, ex); } try { in.close(); } catch (IOException ex) { Logger.getLogger(MyHash.class.getName()).log(Level.SEVERE, null, ex); } } public static int keyIt (int x) { int key = x % 997; return key; } public static int horner (String word){ int length = word.length(); char[] letters = new char[length]; for (int i = 0; i < length; i++){ letters[i]=word.charAt(i); } char[] alphabet = new char[26]; String abc = "abcdefghijklmnopqrstuvwxyz"; for (int i = 0; i < 26; i++){ alphabet[i]=abc.charAt(i); } int[] numbers = new int[length]; int place = 0; for (int i = 0; i < length; i++){ for (int j = 0; j < 26; j++){ if (alphabet[j]==letters[i]){ numbers[place]=j+1; place++; } } } int hornered = numbers[0] * 32; for (int i = 1; i < numbers.length; i++){ hornered += numbers[i]; if (i == numbers.length -1){ return hornered; } hornered = hornered % 997; hornered *= 32; } return hornered; } public static String[] makeReserved (){ reserved[0] = "abstract"; reserved[1] = "assert"; reserved[2] = "boolean"; reserved[3] = "break"; reserved[4] = "byte"; reserved[5] = "case"; reserved[6] = "catch"; reserved[7] = "char"; reserved[8] = "class"; reserved[9] = "const"; reserved[10] = "continue"; reserved[11] = "default"; reserved[12] = "do"; reserved[13] = "double"; reserved[14] = "else"; reserved[15] = "enum"; reserved[16] = "extends"; reserved[17] = "false"; reserved[18] = "final"; reserved[19] = "finally"; reserved[20] = "float"; reserved[21] = "for"; reserved[22] = "goto"; reserved[23] = "if"; reserved[24] = "implements"; reserved[25] = "import"; reserved[26] = "instanceof"; reserved[27] = "int"; reserved[28] = "interface"; reserved[29] = "long"; reserved[30] = "native"; reserved[31] = "new"; reserved[32] = "null"; reserved[33] = "package"; reserved[34] = "private"; reserved[35] = "protected"; reserved[36] = "public"; reserved[37] = "return"; reserved[38] = "short"; reserved[39] = "static"; reserved[40] = "strictfp"; reserved[41] = "super"; reserved[42] = "switch"; reserved[43] = "synchronize"; reserved[44] = "this"; reserved[45] = "throw"; reserved[46] = "throws"; reserved[47] = "trasient"; reserved[48] = "true"; reserved[49] = "try"; reserved[50] = "void"; reserved[51] = "volatile"; reserved[52] = "while"; reserved[53] = "="; reserved[54] = "=="; reserved[55] = "!="; reserved[56] = "+"; reserved[57] = "-"; reserved[58] = "*"; reserved[59] = "/"; reserved[60] = "{"; reserved[61] = "}"; return reserved; } }

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• Automating Solaris 11 Zones Installation Using The Automated Install Server

  - by Orgad Kimchi

  Introduction How to use the Oracle Solaris 11 Automated install server in order to automate the Solaris 11 Zones installation. In this document I will demonstrate how to setup the Automated Install server in order to provide hands off installation process for the Global Zone and two Non Global Zones located on the same system. Architecture layout: Figure 1. Architecture layout Prerequisite Setup the Automated install server (AI) using the following instructions “How to Set Up Automated Installation Services for Oracle Solaris 11” The first step in this setup will be creating two Solaris 11 Zones configuration files. Step 1: Create the Solaris 11 Zones configuration files  The Solaris Zones configuration files should be in the format of the zonecfg export command. # zonecfg -z zone1 export > /var/tmp/zone1# cat /var/tmp/zone1 create -b set brand=solaris set zonepath=/rpool/zones/zone1 set autoboot=true set ip-type=exclusive add anet set linkname=net0 set lower-link=auto set configure-allowed-address=true set link-protection=mac-nospoof set mac-address=random end  Create a backup copy of this file under a different name, for example, zone2. # cp /var/tmp/zone1 /var/tmp/zone2 Modify the second configuration file with the zone2 configuration information You should change the zonepath for example: set zonepath=/rpool/zones/zone2 Step2: Copy and share the Zones configuration files  Create the NFS directory for the Zones configuration files # mkdir /export/zone_config Share the directory for the Zones configuration file # share –o ro /export/zone_config Copy the Zones configuration files into the NFS shared directory # cp /var/tmp/zone1 /var/tmp/zone2  /export/zone_config Verify that the NFS share has been created using the following command # share export_zone_config      /export/zone_config     nfs     sec=sys,ro Step 3: Add the Global Zone as client to the Install Service Use the installadm create-client command to associate client (Global Zone) with the install service To find the MAC address of a system, use the dladm command as described in the dladm(1M) man page. The following command adds the client (Global Zone) with MAC address 0:14:4f:2:a:19 to the s11x86service install service. # installadm create-client -e “0:14:4f:2:a:19" -n s11x86service You can verify the client creation using the following command # installadm list –c Service Name  Client Address     Arch   Image Path ------------  --------------     ----   ---------- s11x86service 00:14:4F:02:0A:19  i386   /export/auto_install/s11x86service We can see the client install service name (s11x86service), MAC address (00:14:4F:02:0A:19 and Architecture (i386). Step 4: Global Zone manifest setup  First, get a list of the installation services and the manifests associated with them: # installadm list -m Service Name   Manifest        Status ------------   --------        ------ default-i386   orig_default   Default s11x86service  orig_default   Default Then probe the s11x86service and the default manifest associated with it. The -m switch reflects the name of the manifest associated with a service. Since we want to capture that output into a file, we redirect the output of the command as follows: # installadm export -n s11x86service -m orig_default >  /var/tmp/orig_default.xml Create a backup copy of this file under a different name, for example, orig-default2.xml, and edit the copy. # cp /var/tmp/orig_default.xml /var/tmp/orig_default2.xml Use the configuration element in the AI manifest for the client system to specify non-global zones. Use the name attribute of the configuration element to specify the name of the zone. Use the source attribute to specify the location of the config file for the zone.The source location can be any http:// or file:// location that the client can access during installation. The following sample AI manifest specifies two Non-Global Zones: zone1 and zone2 You should replace the server_ip with the ip address of the NFS server. <!DOCTYPE auto_install SYSTEM "file:///usr/share/install/ai.dtd.1"> <auto_install>   <ai_instance>     <target>       <logical>         <zpool name="rpool" is_root="true">           <filesystem name="export" mountpoint="/export"/>           <filesystem name="export/home"/>           <be name="solaris"/>         </zpool>       </logical>     </target>     <software type="IPS">       <source>         <publisher name="solaris">           <origin name="http://pkg.oracle.com/solaris/release"/>         </publisher>       </source>       <software_data action="install">         <name>pkg:/entire@latest</name>         <name>pkg:/group/system/solaris-large-server</name>       </software_data>     </software>     <configuration type="zone" name="zone1" source="file:///net/server_ip/export/zone_config/zone1"/>     <configuration type="zone" name="zone2" source="file:///net/server_ip/export/zone_config/zone2"/>   </ai_instance> </auto_install> The following example adds the /var/tmp/orig_default2.xml AI manifest to the s11x86service install service # installadm create-manifest -n s11x86service -f /var/tmp/orig_default2.xml -m gzmanifest You can verify the manifest creation using the following command # installadm list -n s11x86service  -m Service/Manifest Name  Status   Criteria ---------------------  ------   -------- s11x86service    orig_default        Default  None    gzmanifest          Inactive None We can see from the command output that the new manifest named gzmanifest has been created and associated with the s11x86service install service. Step 5: Non Global Zone manifest setup The AI manifest for non-global zone installation is similar to the AI manifest for installing the global zone. If you do not provide a custom AI manifest for a non-global zone, the default AI manifest for Zones is used The default AI manifest for Zones is available at /usr/share/auto_install/manifest/zone_default.xml. In this example we should use the default AI manifest for zones The following sample default AI manifest for zones # cat /usr/share/auto_install/manifest/zone_default.xml <?xml version="1.0" encoding="UTF-8"?> <!--  Copyright (c) 2011, 2012, Oracle and/or its affiliates. All rights reserved. --> <!DOCTYPE auto_install SYSTEM "file:///usr/share/install/ai.dtd.1"> <auto_install>     <ai_instance name="zone_default">         <target>             <logical>                 <zpool name="rpool">                     <!--                       Subsequent <filesystem> entries instruct an installer                       to create following ZFS datasets:                           <root_pool>/export         (mounted on /export)                           <root_pool>/export/home    (mounted on /export/home)                       Those datasets are part of standard environment                       and should be always created.                       In rare cases, if there is a need to deploy a zone                       without these datasets, either comment out or remove                       <filesystem> entries. In such scenario, it has to be also                       assured that in case of non-interactive post-install                       configuration, creation of initial user account is                       disabled in related system configuration profile.                       Otherwise the installed zone would fail to boot.                     -->                     <filesystem name="export" mountpoint="/export"/>                     <filesystem name="export/home"/>                     <be name="solaris">                         <options>                             <option name="compression" value="on"/>                         </options>                     </be>                 </zpool>             </logical>         </target>         <software type="IPS">             <destination>                 <image>                     <!-- Specify locales to install -->                     <facet set="false">facet.locale.*</facet>                     <facet set="true">facet.locale.de</facet>                     <facet set="true">facet.locale.de_DE</facet>                     <facet set="true">facet.locale.en</facet>                     <facet set="true">facet.locale.en_US</facet>                     <facet set="true">facet.locale.es</facet>                     <facet set="true">facet.locale.es_ES</facet>                     <facet set="true">facet.locale.fr</facet>                     <facet set="true">facet.locale.fr_FR</facet>                     <facet set="true">facet.locale.it</facet>                     <facet set="true">facet.locale.it_IT</facet>                     <facet set="true">facet.locale.ja</facet>                     <facet set="true">facet.locale.ja_*</facet>                     <facet set="true">facet.locale.ko</facet>                     <facet set="true">facet.locale.ko_*</facet>                     <facet set="true">facet.locale.pt</facet>                     <facet set="true">facet.locale.pt_BR</facet>                     <facet set="true">facet.locale.zh</facet>                     <facet set="true">facet.locale.zh_CN</facet>                     <facet set="true">facet.locale.zh_TW</facet>                 </image>             </destination>             <software_data action="install">                 <name>pkg:/group/system/solaris-small-server</name>             </software_data>         </software>     </ai_instance> </auto_install> (optional) We can customize the default AI manifest for Zones Create a backup copy of this file under a different name, for example, zone_default2.xml and edit the copy # cp /usr/share/auto_install/manifest/zone_default.xml /var/tmp/zone_default2.xml Edit the copy (/var/tmp/zone_default2.xml) The following example adds the /var/tmp/zone_default2.xml AI manifest to the s11x86service install service and specifies that zone1 and zone2 should use this manifest. # installadm create-manifest -n s11x86service -f /var/tmp/zone_default2.xml -m zones_manifest -c zonename="zone1 zone2" Note: Do not use the following elements or attributes in a non-global zone AI manifest:     The auto_reboot attribute of the ai_instance element     The http_proxy attribute of the ai_instance element     The disk child element of the target element     The noswap attribute of the logical element     The nodump attribute of the logical element     The configuration element Step 6: Global Zone profile setup We are going to create a global zone configuration profile which includes the host information for example: host name, ip address name services etc… # sysconfig create-profile –o /var/tmp/gz_profile.xml You need to provide the host information for example:     Default router     Root password     DNS information The output should eventually disappear and be replaced by the initial screen of the System Configuration Tool (see Figure 2), where you can do the final configuration. Figure 2. Profile creation menu You can validate the profile using the following command # installadm validate -n s11x86service –P /var/tmp/gz_profile.xml Validating static profile gz_profile.xml...  Passed Next, instantiate a profile with the install service. In our case, use the following syntax for doing this # installadm create-profile -n s11x86service  -f /var/tmp/gz_profile.xml -p  gz_profile You can verify profile creation using the following command # installadm list –n s11x86service  -p Service/Profile Name  Criteria --------------------  -------- s11x86service    gz_profile         None We can see that the gz_profie has been created and associated with the s11x86service Install service. Step 7: Setup the Solaris Zones configuration profiles The step should be similar to the Global zone profile creation on step 6 # sysconfig create-profile –o /var/tmp/zone1_profile.xml # sysconfig create-profile –o /var/tmp/zone2_profile.xml You can validate the profiles using the following command # installadm validate -n s11x86service -P /var/tmp/zone1_profile.xml Validating static profile zone1_profile.xml...  Passed # installadm validate -n s11x86service -P /var/tmp/zone2_profile.xml Validating static profile zone2_profile.xml...  Passed Next, associate the profiles with the install service The following example adds the zone1_profile.xml configuration profile to the s11x86service  install service and specifies that zone1 should use this profile. # installadm create-profile -n s11x86service  -f  /var/tmp/zone1_profile.xml -p zone1_profile -c zonename=zone1 The following example adds the zone2_profile.xml configuration profile to the s11x86service  install service and specifies that zone2 should use this profile. # installadm create-profile -n s11x86service  -f  /var/tmp/zone2_profile.xml -p zone2_profile -c zonename=zone2 You can verify the profiles creation using the following command # installadm list -n s11x86service -p Service/Profile Name  Criteria --------------------  -------- s11x86service    zone1_profile      zonename = zone1    zone2_profile      zonename = zone2    gz_profile         None We can see that we have three profiles in the s11x86service  install service     Global Zone  gz_profile     zone1            zone1_profile     zone2            zone2_profile. Step 8: Global Zone setup Associate the global zone client with the manifest and the profile that we create in the previous steps The following example adds the manifest and profile to the client (global zone), where: gzmanifest  is the name of the manifest. gz_profile  is the name of the configuration profile. mac="0:14:4f:2:a:19" is the client (global zone) mac address s11x86service is the install service name. # installadm set-criteria -m  gzmanifest  –p  gz_profile  -c mac="0:14:4f:2:a:19" -n s11x86service You can verify the manifest and profile association using the following command # installadm list -n s11x86service -p  -m Service/Manifest Name  Status   Criteria ---------------------  ------   -------- s11x86service    gzmanifest                   mac  = 00:14:4F:02:0A:19    orig_default        Default  None Service/Profile Name  Criteria --------------------  -------- s11x86service    gz_profile         mac      = 00:14:4F:02:0A:19    zone2_profile      zonename = zone2    zone1_profile      zonename = zone1 Step 9: Provision the host with the Non-Global Zones The next step is to boot the client system off the network and provision it using the Automated Install service that we just set up. First, boot the client system. Figure 3 shows the network boot attempt (when done on an x86 system): Figure 3. Network Boot Then you will be prompted by a GRUB menu, with a timer, as shown in Figure 4. The default selection (the "Text Installer and command line" option) is highlighted.  Press the down arrow to highlight the second option labeled Automated Install, and then press Enter. The reason we need to do this is because we want to prevent a system from being automatically re-installed if it were to be booted from the network accidentally. Figure 4. GRUB Menu What follows is the continuation of a networked boot from the Automated Install server,. The client downloads a mini-root (a small set of files in which to successfully run the installer), identifies the location of the Automated Install manifest on the network, retrieves that manifest, and then processes it to identify the address of the IPS repository from which to obtain the desired software payload. Non-Global Zones are installed and configured on the first reboot after the Global Zone is installed. You can list all the Solaris Zones status using the following command # zoneadm list -civ Once the Zones are in running state you can login into the Zone using the following command # zlogin –z zone1 Troubleshooting Automated Installations If an installation to a client system failed, you can find the client log at /system/volatile/install_log. NOTE: Zones are not installed if any of the following errors occurs:     A zone config file is not syntactically correct.     A collision exists among zone names, zone paths, or delegated ZFS datasets in the set of zones to be installed     Required datasets are not configured in the global zone. For more troubleshooting information see “Installing Oracle Solaris 11 Systems” Conclusion This paper demonstrated the benefits of using the Automated Install server to simplify the Non Global Zones setup, including the creation and configuration of the global zone manifest and the Solaris Zones profiles.

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• Using R to Analyze G1GC Log Files

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  Using R to Analyze G1GC Log Files   Using R to Analyze G1GC Log Files Introduction Working in Oracle Platform Integration gives an engineer opportunities to work on a wide array of technologies. My team’s goal is to make Oracle applications run best on the Solaris/SPARC platform. When looking for bottlenecks in a modern applications, one needs to be aware of not only how the CPUs and operating system are executing, but also network, storage, and in some cases, the Java Virtual Machine. I was recently presented with about 1.5 GB of Java Garbage First Garbage Collector log file data. If you’re not familiar with the subject, you might want to review Garbage First Garbage Collector Tuning by Monica Beckwith. The customer had been running Java HotSpot 1.6.0_31 to host a web application server. I was told that the Solaris/SPARC server was running a Java process launched using a commmand line that included the following flags: -d64 -Xms9g -Xmx9g -XX:+UseG1GC -XX:MaxGCPauseMillis=200 -XX:InitiatingHeapOccupancyPercent=80 -XX:PermSize=256m -XX:MaxPermSize=256m -XX:+PrintGC -XX:+PrintGCTimeStamps -XX:+PrintHeapAtGC -XX:+PrintGCDateStamps -XX:+PrintFlagsFinal -XX:+DisableExplicitGC -XX:+UnlockExperimentalVMOptions -XX:ParallelGCThreads=8 Several sources on the internet indicate that if I were to print out the 1.5 GB of log files, it would require enough paper to fill the bed of a pick up truck. Of course, it would be fruitless to try to scan the log files by hand. Tools will be required to summarize the contents of the log files. Others have encountered large Java garbage collection log files. There are existing tools to analyze the log files: IBM’s GC toolkit The chewiebug GCViewer gchisto HPjmeter Instead of using one of the other tools listed, I decide to parse the log files with standard Unix tools, and analyze the data with R. Data Cleansing The log files arrived in two different formats. I guess that the difference is that one set of log files was generated using a more verbose option, maybe -XX:+PrintHeapAtGC, and the other set of log files was generated without that option. Format 1 In some of the log files, the log files with the less verbose format, a single trace, i.e. the report of a singe garbage collection event, looks like this: {Heap before GC invocations=12280 (full 61): garbage-first heap total 9437184K, used 7499918K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) region size 4096K, 1 young (4096K), 0 survivors (0K) compacting perm gen total 262144K, used 144077K [0xffffffff40000000, 0xffffffff50000000, 0xffffffff50000000) the space 262144K, 54% used [0xffffffff40000000, 0xffffffff48cb3758, 0xffffffff48cb3800, 0xffffffff50000000) No shared spaces configured. 2014-05-14T07:24:00.988-0700: 60586.353: [GC pause (young) 7324M->7320M(9216M), 0.1567265 secs] Heap after GC invocations=12281 (full 61): garbage-first heap total 9437184K, used 7496533K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) region size 4096K, 0 young (0K), 0 survivors (0K) compacting perm gen total 262144K, used 144077K [0xffffffff40000000, 0xffffffff50000000, 0xffffffff50000000) the space 262144K, 54% used [0xffffffff40000000, 0xffffffff48cb3758, 0xffffffff48cb3800, 0xffffffff50000000) No shared spaces configured. } A simple grep can be used to extract a summary: $ grep "\[ GC pause (young" g1gc.log 2014-05-13T13:24:35.091-0700: 3.109: [GC pause (young) 20M->5029K(9216M), 0.0146328 secs] 2014-05-13T13:24:35.440-0700: 3.459: [GC pause (young) 9125K->6077K(9216M), 0.0086723 secs] 2014-05-13T13:24:37.581-0700: 5.599: [GC pause (young) 25M->8470K(9216M), 0.0203820 secs] 2014-05-13T13:24:42.686-0700: 10.704: [GC pause (young) 44M->15M(9216M), 0.0288848 secs] 2014-05-13T13:24:48.941-0700: 16.958: [GC pause (young) 51M->20M(9216M), 0.0491244 secs] 2014-05-13T13:24:56.049-0700: 24.066: [GC pause (young) 92M->26M(9216M), 0.0525368 secs] 2014-05-13T13:25:34.368-0700: 62.383: [GC pause (young) 602M->68M(9216M), 0.1721173 secs] But that format wasn't easily read into R, so I needed to be a bit more tricky. I used the following Unix command to create a summary file that was easy for R to read. $ echo "SecondsSinceLaunch BeforeSize AfterSize TotalSize RealTime" $ grep "\[GC pause (young" g1gc.log | grep -v mark | sed -e 's/[A-SU-z\(\),]/ /g' -e 's/->/ /' -e 's/: / /g' | more SecondsSinceLaunch BeforeSize AfterSize TotalSize RealTime 2014-05-13T13:24:35.091-0700 3.109 20 5029 9216 0.0146328 2014-05-13T13:24:35.440-0700 3.459 9125 6077 9216 0.0086723 2014-05-13T13:24:37.581-0700 5.599 25 8470 9216 0.0203820 2014-05-13T13:24:42.686-0700 10.704 44 15 9216 0.0288848 2014-05-13T13:24:48.941-0700 16.958 51 20 9216 0.0491244 2014-05-13T13:24:56.049-0700 24.066 92 26 9216 0.0525368 2014-05-13T13:25:34.368-0700 62.383 602 68 9216 0.1721173 Format 2 In some of the log files, the log files with the more verbose format, a single trace, i.e. the report of a singe garbage collection event, was more complicated than Format 1. Here is a text file with an example of a single G1GC trace in the second format. As you can see, it is quite complicated. It is nice that there is so much information available, but the level of detail can be overwhelming. I wrote this awk script (download) to summarize each trace on a single line. #!/usr/bin/env awk -f BEGIN { printf("SecondsSinceLaunch IncrementalCount FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize\n") } ###################### # Save count data from lines that are at the start of each G1GC trace. # Each trace starts out like this: # {Heap before GC invocations=14 (full 0): # garbage-first heap total 9437184K, used 325496K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) ###################### /{Heap.*full/{ gsub ( "\\)" , "" ); nf=split($0,a,"="); split(a[2],b," "); getline; if ( match($0, "first") ) { G1GC=1; IncrementalCount=b[1]; FullCount=substr( b[3], 1, length(b[3])-1 ); } else { G1GC=0; } } ###################### # Pull out time stamps that are in lines with this format: # 2014-05-12T14:02:06.025-0700: 94.312: [GC pause (young), 0.08870154 secs] ###################### /GC pause/ { DateTime=$1; SecondsSinceLaunch=substr($2, 1, length($2)-1); } ###################### # Heap sizes are in lines that look like this: # [ 4842M->4838M(9216M)] ###################### /\[ .*]$/ { gsub ( "\\[" , "" ); gsub ( "\ \]" , "" ); gsub ( "->" , " " ); gsub ( "\\( " , " " ); gsub ( "\ \)" , " " ); split($0,a," "); if ( split(a[1],b,"M") > 1 ) {BeforeSize=b[1]*1024;} if ( split(a[1],b,"K") > 1 ) {BeforeSize=b[1];} if ( split(a[2],b,"M") > 1 ) {AfterSize=b[1]*1024;} if ( split(a[2],b,"K") > 1 ) {AfterSize=b[1];} if ( split(a[3],b,"M") > 1 ) {TotalSize=b[1]*1024;} if ( split(a[3],b,"K") > 1 ) {TotalSize=b[1];} } ###################### # Emit an output line when you find input that looks like this: # [Times: user=1.41 sys=0.08, real=0.24 secs] ###################### /\[Times/ { if (G1GC==1) { gsub ( "," , "" ); split($2,a,"="); UserTime=a[2]; split($3,a,"="); SysTime=a[2]; split($4,a,"="); RealTime=a[2]; print DateTime,SecondsSinceLaunch,IncrementalCount,FullCount,UserTime,SysTime,RealTime,BeforeSize,AfterSize,TotalSize; G1GC=0; } } The resulting summary is about 25X smaller that the original file, but still difficult for a human to digest. SecondsSinceLaunch IncrementalCount FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ... 2014-05-12T18:36:34.669-0700: 3985.744 561 0 0.57 0.06 0.16 1724416 1720320 9437184 2014-05-12T18:36:34.839-0700: 3985.914 562 0 0.51 0.06 0.19 1724416 1720320 9437184 2014-05-12T18:36:35.069-0700: 3986.144 563 0 0.60 0.04 0.27 1724416 1721344 9437184 2014-05-12T18:36:35.354-0700: 3986.429 564 0 0.33 0.04 0.09 1725440 1722368 9437184 2014-05-12T18:36:35.545-0700: 3986.620 565 0 0.58 0.04 0.17 1726464 1722368 9437184 2014-05-12T18:36:35.726-0700: 3986.801 566 0 0.43 0.05 0.12 1726464 1722368 9437184 2014-05-12T18:36:35.856-0700: 3986.930 567 0 0.30 0.04 0.07 1726464 1723392 9437184 2014-05-12T18:36:35.947-0700: 3987.023 568 0 0.61 0.04 0.26 1727488 1723392 9437184 2014-05-12T18:36:36.228-0700: 3987.302 569 0 0.46 0.04 0.16 1731584 1724416 9437184 Reading the Data into R Once the GC log data had been cleansed, either by processing the first format with the shell script, or by processing the second format with the awk script, it was easy to read the data into R. g1gc.df = read.csv("summary.txt", row.names = NULL, stringsAsFactors=FALSE,sep="") str(g1gc.df) ## 'data.frame': 8307 obs. of 10 variables: ## $ row.names : chr "2014-05-12T14:00:32.868-0700:" "2014-05-12T14:00:33.179-0700:" "2014-05-12T14:00:33.677-0700:" "2014-05-12T14:00:35.538-0700:" ... ## $ SecondsSinceLaunch: num 1.16 1.47 1.97 3.83 6.1 ... ## $ IncrementalCount : int 0 1 2 3 4 5 6 7 8 9 ... ## $ FullCount : int 0 0 0 0 0 0 0 0 0 0 ... ## $ UserTime : num 0.11 0.05 0.04 0.21 0.08 0.26 0.31 0.33 0.34 0.56 ... ## $ SysTime : num 0.04 0.01 0.01 0.05 0.01 0.06 0.07 0.06 0.07 0.09 ... ## $ RealTime : num 0.02 0.02 0.01 0.04 0.02 0.04 0.05 0.04 0.04 0.06 ... ## $ BeforeSize : int 8192 5496 5768 22528 24576 43008 34816 53248 55296 93184 ... ## $ AfterSize : int 1400 1672 2557 4907 7072 14336 16384 18432 19456 21504 ... ## $ TotalSize : int 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 ... head(g1gc.df) ## row.names SecondsSinceLaunch IncrementalCount ## 1 2014-05-12T14:00:32.868-0700: 1.161 0 ## 2 2014-05-12T14:00:33.179-0700: 1.472 1 ## 3 2014-05-12T14:00:33.677-0700: 1.969 2 ## 4 2014-05-12T14:00:35.538-0700: 3.830 3 ## 5 2014-05-12T14:00:37.811-0700: 6.103 4 ## 6 2014-05-12T14:00:41.428-0700: 9.720 5 ## FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ## 1 0 0.11 0.04 0.02 8192 1400 9437184 ## 2 0 0.05 0.01 0.02 5496 1672 9437184 ## 3 0 0.04 0.01 0.01 5768 2557 9437184 ## 4 0 0.21 0.05 0.04 22528 4907 9437184 ## 5 0 0.08 0.01 0.02 24576 7072 9437184 ## 6 0 0.26 0.06 0.04 43008 14336 9437184 Basic Statistics Once the data has been read into R, simple statistics are very easy to generate. All of the numbers from high school statistics are available via simple commands. For example, generate a summary of every column: summary(g1gc.df) ## row.names SecondsSinceLaunch IncrementalCount FullCount ## Length:8307 Min. : 1 Min. : 0 Min. : 0.0 ## Class :character 1st Qu.: 9977 1st Qu.:2048 1st Qu.: 0.0 ## Mode :character Median :12855 Median :4136 Median : 12.0 ## Mean :12527 Mean :4156 Mean : 31.6 ## 3rd Qu.:15758 3rd Qu.:6262 3rd Qu.: 61.0 ## Max. :55484 Max. :8391 Max. :113.0 ## UserTime SysTime RealTime BeforeSize ## Min. :0.040 Min. :0.0000 Min. : 0.0 Min. : 5476 ## 1st Qu.:0.470 1st Qu.:0.0300 1st Qu.: 0.1 1st Qu.:5137920 ## Median :0.620 Median :0.0300 Median : 0.1 Median :6574080 ## Mean :0.751 Mean :0.0355 Mean : 0.3 Mean :5841855 ## 3rd Qu.:0.920 3rd Qu.:0.0400 3rd Qu.: 0.2 3rd Qu.:7084032 ## Max. :3.370 Max. :1.5600 Max. :488.1 Max. :8696832 ## AfterSize TotalSize ## Min. : 1380 Min. :9437184 ## 1st Qu.:5002752 1st Qu.:9437184 ## Median :6559744 Median :9437184 ## Mean :5785454 Mean :9437184 ## 3rd Qu.:7054336 3rd Qu.:9437184 ## Max. :8482816 Max. :9437184 Q: What is the total amount of User CPU time spent in garbage collection? sum(g1gc.df$UserTime) ## [1] 6236 As you can see, less than two hours of CPU time was spent in garbage collection. Is that too much? To find the percentage of time spent in garbage collection, divide the number above by total_elapsed_time*CPU_count. In this case, there are a lot of CPU’s and it turns out the the overall amount of CPU time spent in garbage collection isn’t a problem when viewed in isolation. When calculating rates, i.e. events per unit time, you need to ask yourself if the rate is homogenous across the time period in the log file. Does the log file include spikes of high activity that should be separately analyzed? Averaging in data from nights and weekends with data from business hours may alias problems. If you have a reason to suspect that the garbage collection rates include peaks and valleys that need independent analysis, see the “Time Series” section, below. Q: How much garbage is collected on each pass? The amount of heap space that is recovered per GC pass is surprisingly low: At least one collection didn’t recover any data. (“Min.=0”) 25% of the passes recovered 3MB or less. (“1st Qu.=3072”) Half of the GC passes recovered 4MB or less. (“Median=4096”) The average amount recovered was 56MB. (“Mean=56390”) 75% of the passes recovered 36MB or less. (“3rd Qu.=36860”) At least one pass recovered 2GB. (“Max.=2121000”) g1gc.df$Delta = g1gc.df$BeforeSize - g1gc.df$AfterSize summary(g1gc.df$Delta) ## Min. 1st Qu. Median Mean 3rd Qu. Max. ## 0 3070 4100 56400 36900 2120000 Q: What is the maximum User CPU time for a single collection? The worst garbage collection (“Max.”) is many standard deviations away from the mean. The data appears to be right skewed. summary(g1gc.df$UserTime) ## Min. 1st Qu. Median Mean 3rd Qu. Max. ## 0.040 0.470 0.620 0.751 0.920 3.370 sd(g1gc.df$UserTime) ## [1] 0.3966 Basic Graphics Once the data is in R, it is trivial to plot the data with formats including dot plots, line charts, bar charts (simple, stacked, grouped), pie charts, boxplots, scatter plots histograms, and kernel density plots. Histogram of User CPU Time per Collection I don't think that this graph requires any explanation. hist(g1gc.df$UserTime, main="User CPU Time per Collection", xlab="Seconds", ylab="Frequency") Box plot to identify outliers When the initial data is viewed with a box plot, you can see the one crazy outlier in the real time per GC. Save this data point for future analysis and drop the outlier so that it’s not throwing off our statistics. Now the box plot shows many outliers, which will be examined later, using times series analysis. Notice that the scale of the x-axis changes drastically once the crazy outlier is removed. par(mfrow=c(2,1)) boxplot(g1gc.df$UserTime,g1gc.df$SysTime,g1gc.df$RealTime, main="Box Plot of Time per GC\n(dominated by a crazy outlier)", names=c("usr","sys","elapsed"), xlab="Seconds per GC", ylab="Time (Seconds)", horizontal = TRUE, outcol="red") crazy.outlier.df=g1gc.df[g1gc.df$RealTime > 400,] g1gc.df=g1gc.df[g1gc.df$RealTime < 400,] boxplot(g1gc.df$UserTime,g1gc.df$SysTime,g1gc.df$RealTime, main="Box Plot of Time per GC\n(crazy outlier excluded)", names=c("usr","sys","elapsed"), xlab="Seconds per GC", ylab="Time (Seconds)", horizontal = TRUE, outcol="red") box(which = "outer", lty = "solid") Here is the crazy outlier for future analysis: crazy.outlier.df ## row.names SecondsSinceLaunch IncrementalCount ## 8233 2014-05-12T23:15:43.903-0700: 20741 8316 ## FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ## 8233 112 0.55 0.42 488.1 8381440 8235008 9437184 ## Delta ## 8233 146432 R Time Series Data To analyze the garbage collection as a time series, I’ll use Z’s Ordered Observations (zoo). “zoo is the creator for an S3 class of indexed totally ordered observations which includes irregular time series.” require(zoo) ## Loading required package: zoo ## ## Attaching package: 'zoo' ## ## The following objects are masked from 'package:base': ## ## as.Date, as.Date.numeric head(g1gc.df[,1]) ## [1] "2014-05-12T14:00:32.868-0700:" "2014-05-12T14:00:33.179-0700:" ## [3] "2014-05-12T14:00:33.677-0700:" "2014-05-12T14:00:35.538-0700:" ## [5] "2014-05-12T14:00:37.811-0700:" "2014-05-12T14:00:41.428-0700:" options("digits.secs"=3) times=as.POSIXct( g1gc.df[,1], format="%Y-%m-%dT%H:%M:%OS%z:") g1gc.z = zoo(g1gc.df[,-c(1)], order.by=times) head(g1gc.z) ## SecondsSinceLaunch IncrementalCount FullCount ## 2014-05-12 17:00:32.868 1.161 0 0 ## 2014-05-12 17:00:33.178 1.472 1 0 ## 2014-05-12 17:00:33.677 1.969 2 0 ## 2014-05-12 17:00:35.538 3.830 3 0 ## 2014-05-12 17:00:37.811 6.103 4 0 ## 2014-05-12 17:00:41.427 9.720 5 0 ## UserTime SysTime RealTime BeforeSize AfterSize ## 2014-05-12 17:00:32.868 0.11 0.04 0.02 8192 1400 ## 2014-05-12 17:00:33.178 0.05 0.01 0.02 5496 1672 ## 2014-05-12 17:00:33.677 0.04 0.01 0.01 5768 2557 ## 2014-05-12 17:00:35.538 0.21 0.05 0.04 22528 4907 ## 2014-05-12 17:00:37.811 0.08 0.01 0.02 24576 7072 ## 2014-05-12 17:00:41.427 0.26 0.06 0.04 43008 14336 ## TotalSize Delta ## 2014-05-12 17:00:32.868 9437184 6792 ## 2014-05-12 17:00:33.178 9437184 3824 ## 2014-05-12 17:00:33.677 9437184 3211 ## 2014-05-12 17:00:35.538 9437184 17621 ## 2014-05-12 17:00:37.811 9437184 17504 ## 2014-05-12 17:00:41.427 9437184 28672 Example of Two Benchmark Runs in One Log File The data in the following graph is from a different log file, not the one of primary interest to this article. I’m including this image because it is an example of idle periods followed by busy periods. It would be uninteresting to average the rate of garbage collection over the entire log file period. More interesting would be the rate of garbage collect in the two busy periods. Are they the same or different? Your production data may be similar, for example, bursts when employees return from lunch and idle times on weekend evenings, etc. Once the data is in an R Time Series, you can analyze isolated time windows. Clipping the Time Series data Flashing back to our test case… Viewing the data as a time series is interesting. You can see that the work intensive time period is between 9:00 PM and 3:00 AM. Lets clip the data to the interesting period:     par(mfrow=c(2,1)) plot(g1gc.z$UserTime, type="h", main="User Time per GC\nTime: Complete Log File", xlab="Time of Day", ylab="CPU Seconds per GC", col="#1b9e77") clipped.g1gc.z=window(g1gc.z, start=as.POSIXct("2014-05-12 21:00:00"), end=as.POSIXct("2014-05-13 03:00:00")) plot(clipped.g1gc.z$UserTime, type="h", main="User Time per GC\nTime: Limited to Benchmark Execution", xlab="Time of Day", ylab="CPU Seconds per GC", col="#1b9e77") box(which = "outer", lty = "solid") Cumulative Incremental and Full GC count Here is the cumulative incremental and full GC count. When the line is very steep, it indicates that the GCs are repeating very quickly. Notice that the scale on the Y axis is different for full vs. incremental. plot(clipped.g1gc.z[,c(2:3)], main="Cumulative Incremental and Full GC count", xlab="Time of Day", col="#1b9e77") GC Analysis of Benchmark Execution using Time Series data In the following series of 3 graphs: The “After Size” show the amount of heap space in use after each garbage collection. Many Java objects are still referenced, i.e. alive, during each garbage collection. This may indicate that the application has a memory leak, or may indicate that the application has a very large memory footprint. Typically, an application's memory footprint plateau's in the early stage of execution. One would expect this graph to have a flat top. The steep decline in the heap space may indicate that the application crashed after 2:00. The second graph shows that the outliers in real execution time, discussed above, occur near 2:00. when the Java heap seems to be quite full. The third graph shows that Full GCs are infrequent during the first few hours of execution. The rate of Full GC's, (the slope of the cummulative Full GC line), changes near midnight.   plot(clipped.g1gc.z[,c("AfterSize","RealTime","FullCount")], xlab="Time of Day", col=c("#1b9e77","red","#1b9e77")) GC Analysis of heap recovered Each GC trace includes the amount of heap space in use before and after the individual GC event. During garbage coolection, unreferenced objects are identified, the space holding the unreferenced objects is freed, and thus, the difference in before and after usage indicates how much space has been freed. The following box plot and bar chart both demonstrate the same point - the amount of heap space freed per garbage colloection is surprisingly low. par(mfrow=c(2,1)) boxplot(as.vector(clipped.g1gc.z$Delta), main="Amount of Heap Recovered per GC Pass", xlab="Size in KB", horizontal = TRUE, col="red") hist(as.vector(clipped.g1gc.z$Delta), main="Amount of Heap Recovered per GC Pass", xlab="Size in KB", breaks=100, col="red") box(which = "outer", lty = "solid") This graph is the most interesting. The dark blue area shows how much heap is occupied by referenced Java objects. This represents memory that holds live data. The red fringe at the top shows how much data was recovered after each garbage collection. barplot(clipped.g1gc.z[,c("AfterSize","Delta")], col=c("#7570b3","#e7298a"), xlab="Time of Day", border=NA) legend("topleft", c("Live Objects","Heap Recovered on GC"), fill=c("#7570b3","#e7298a")) box(which = "outer", lty = "solid") When I discuss the data in the log files with the customer, I will ask for an explaination for the large amount of referenced data resident in the Java heap. There are two are posibilities: There is a memory leak and the amount of space required to hold referenced objects will continue to grow, limited only by the maximum heap size. After the maximum heap size is reached, the JVM will throw an “Out of Memory” exception every time that the application tries to allocate a new object. If this is the case, the aplication needs to be debugged to identify why old objects are referenced when they are no longer needed. The application has a legitimate requirement to keep a large amount of data in memory. The customer may want to further increase the maximum heap size. Another possible solution would be to partition the application across multiple cluster nodes, where each node has responsibility for managing a unique subset of the data. Conclusion In conclusion, R is a very powerful tool for the analysis of Java garbage collection log files. The primary difficulty is data cleansing so that information can be read into an R data frame. Once the data has been read into R, a rich set of tools may be used for thorough evaluation.

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• Simple Physics Simulation in java not working.

  - by Static Void Main

  Dear experts, I wanted to implement ball physics and as i m newbie, i adapt the code in tutorial http://adam21.web.officelive.com/Documents/JavaPhysicsTutorial.pdf . i try to follow that as i much as i can, but i m not able to apply all physical phenomenon in code, can somebody please tell me, where i m mistaken or i m still doing some silly programming mistake. The balls are moving when i m not calling bounce method and i m unable to avail the bounce method and ball are moving towards left side instead of falling/ending on floor**, Can some body recommend me some better way or similar easy compact way to accomplish this task of applying physics on two ball or more balls with interactivity. here is code ; import java.awt.*; public class AdobeBall { protected int radius = 20; protected Color color; // ... Constants final static int DIAMETER = 40; // ... Instance variables private int m_x; // x and y coordinates upper left private int m_y; private double dx = 3.0; // delta x and y private double dy = 6.0; private double m_velocityX; // Pixels to move each time move() is called. private double m_velocityY; private int m_rightBound; // Maximum permissible x, y values. private int m_bottomBound; public AdobeBall(int x, int y, double velocityX, double velocityY, Color color1) { super(); m_x = x; m_y = y; m_velocityX = velocityX; m_velocityY = velocityY; color = color1; } public double getSpeed() { return Math.sqrt((m_x + m_velocityX - m_x) * (m_x + m_velocityX - m_x) + (m_y + m_velocityY - m_y) * (m_y + m_velocityY - m_y)); } public void setSpeed(double speed) { double currentSpeed = Math.sqrt(dx * dx + dy * dy); dx = dx * speed / currentSpeed; dy = dy * speed / currentSpeed; } public void setDirection(double direction) { m_velocityX = (int) (Math.cos(direction) * getSpeed()); m_velocityY = (int) (Math.sin(direction) * getSpeed()); } public double getDirection() { double h = ((m_x + dx - m_x) * (m_x + dx - m_x)) + ((m_y + dy - m_y) * (m_y + dy - m_y)); double a = (m_x + dx - m_x) / h; return a; } // ======================================================== setBounds public void setBounds(int width, int height) { m_rightBound = width - DIAMETER; m_bottomBound = height - DIAMETER; } // ============================================================== move public void move() { double gravAmount = 0.02; double gravDir = 90; // The direction for the gravity to be in. // ... Move the ball at the give velocity. m_x += m_velocityX; m_y += m_velocityY; // ... Bounce the ball off the walls if necessary. if (m_x < 0) { // If at or beyond left side m_x = 0; // Place against edge and m_velocityX = -m_velocityX; } else if (m_x > m_rightBound) { // If at or beyond right side m_x = m_rightBound; // Place against right edge. m_velocityX = -m_velocityX; } if (m_y < 0) { // if we're at top m_y = 0; m_velocityY = -m_velocityY; } else if (m_y > m_bottomBound) { // if we're at bottom m_y = m_bottomBound; m_velocityY = -m_velocityY; } // double speed = Math.sqrt((m_velocityX * m_velocityX) // + (m_velocityY * m_velocityY)); // ...Friction stuff double fricMax = 0.02; // You can use any number, preferably less than 1 double friction = getSpeed(); if (friction > fricMax) friction = fricMax; if (m_velocityX >= 0) { m_velocityX -= friction; } if (m_velocityX <= 0) { m_velocityX += friction; } if (m_velocityY >= 0) { m_velocityY -= friction; } if (m_velocityY <= 0) { m_velocityY += friction; } // ...Gravity stuff m_velocityX += Math.cos(gravDir) * gravAmount; m_velocityY += Math.sin(gravDir) * gravAmount; } public Color getColor() { return color; } public void setColor(Color newColor) { color = newColor; } // ============================================= getDiameter, getX, getY public int getDiameter() { return DIAMETER; } public double getRadius() { return radius; // radius should be a local variable in Ball. } public int getX() { return m_x; } public int getY() { return m_y; } } using adobeBall: import java.awt.*; import java.awt.event.*; import javax.swing.*; public class AdobeBallImplementation implements Runnable { private static final long serialVersionUID = 1L; private volatile boolean Play; private long mFrameDelay; private JFrame frame; private MyKeyListener pit; /** true means mouse was pressed in ball and still in panel. */ private boolean _canDrag = false; private static final int MAX_BALLS = 50; // max number allowed private int currentNumBalls = 2; // number currently active private AdobeBall[] ball = new AdobeBall[MAX_BALLS]; public AdobeBallImplementation(Color ballColor) { frame = new JFrame("simple gaming loop in java"); frame.setSize(400, 400); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); pit = new MyKeyListener(); pit.setPreferredSize(new Dimension(400, 400)); frame.setContentPane(pit); ball[0] = new AdobeBall(34, 150, 7, 2, Color.YELLOW); ball[1] = new AdobeBall(50, 50, 5, 3, Color.BLUE); frame.pack(); frame.setVisible(true); frame.setBackground(Color.white); start(); frame.addMouseListener(pit); frame.addMouseMotionListener(pit); } public void start() { Play = true; Thread t = new Thread(this); t.start(); } public void stop() { Play = false; } public void run() { while (Play == true) { // bounce(ball[0],ball[1]); runball(); pit.repaint(); try { Thread.sleep(mFrameDelay); } catch (InterruptedException ie) { stop(); } } } public void drawworld(Graphics g) { for (int i = 0; i < currentNumBalls; i++) { g.setColor(ball[i].getColor()); g.fillOval(ball[i].getX(), ball[i].getY(), 40, 40); } } public double pointDistance (double x1, double y1, double x2, double y2) { return Math.sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1)); } public void runball() { while (Play == true) { try { for (int i = 0; i < currentNumBalls; i++) { for (int j = 0; j < currentNumBalls; j++) { if (pointDistance(ball[i].getX(), ball[i].getY(), ball[j].getX(), ball[j].getY()) < ball[i] .getRadius() + ball[j].getRadius() + 2) { // bounce(ball[i],ball[j]); ball[i].setBounds(pit.getWidth(), pit.getHeight()); ball[i].move(); pit.repaint(); } } } try { Thread.sleep(50); } catch (Exception e) { System.exit(0); } } catch (Exception e) { e.printStackTrace(); } } } public static double pointDirection(int x1, int y1, int x2, int y2) { double H = Math.sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1)); // The // hypotenuse double x = x2 - x1; // The opposite double y = y2 - y1; // The adjacent double angle = Math.acos(x / H); angle = angle * 57.2960285258; if (y < 0) { angle = 360 - angle; } return angle; } public static void bounce(AdobeBall b1, AdobeBall b2) { if (b2.getSpeed() == 0 && b1.getSpeed() == 0) { // Both balls are stopped. b1.setDirection(pointDirection(b1.getX(), b1.getY(), b2.getX(), b2 .getY())); b2.setDirection(pointDirection(b2.getX(), b2.getY(), b1.getX(), b1 .getY())); b1.setSpeed(1); b2.setSpeed(1); } else if (b2.getSpeed() == 0 && b1.getSpeed() != 0) { // B1 is moving. B2 is stationary. double angle = pointDirection(b1.getX(), b1.getY(), b2.getX(), b2 .getY()); b2.setSpeed(b1.getSpeed()); b2.setDirection(angle); b1.setDirection(angle - 90); } else if (b1.getSpeed() == 0 && b2.getSpeed() != 0) { // B1 is moving. B2 is stationary. double angle = pointDirection(b2.getX(), b2.getY(), b1.getX(), b1 .getY()); b1.setSpeed(b2.getSpeed()); b1.setDirection(angle); b2.setDirection(angle - 90); } else { // Both balls are moving. AdobeBall tmp = b1; double angle = pointDirection(b2.getX(), b2.getY(), b1.getX(), b1 .getY()); double origangle = b1.getDirection(); b1.setDirection(angle + origangle); angle = pointDirection(tmp.getX(), tmp.getY(), b2.getX(), b2.getY()); origangle = b2.getDirection(); b2.setDirection(angle + origangle); } } public static void main(String[] args) { javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { new AdobeBallImplementation(Color.red); } }); } } *EDIT:*ok splitting the code using new approach for gravity from this forum: this code also not working the ball is not coming on floor: public void mymove() { m_x += m_velocityX; m_y += m_velocityY; if (m_y + m_bottomBound > 400) { m_velocityY *= -0.981; // setY(400 - m_bottomBound); m_y = 400 - m_bottomBound; } // ... Bounce the ball off the walls if necessary. if (m_x < 0) { // If at or beyond left side m_x = 0; // Place against edge and m_velocityX = -m_velocityX; } else if (m_x > m_rightBound) { // If at or beyond right side m_x = m_rightBound - 20; // Place against right edge. m_velocityX = -m_velocityX; } if (m_y < 0) { // if we're at top m_y = 1; m_velocityY = -m_velocityY; } else if (m_y > m_bottomBound) { // if we're at bottom m_y = m_bottomBound - 20; m_velocityY = -m_velocityY; } } thanks a lot for any correction and help. jibby

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• error while installing the libmemcached

  - by Ahmet vardar

  I get this while installing libmemcached root@server [/libmemcached]# make make all-am make[1]: Entering directory `/libmemcached' if /bin/sh ./libtool --tag=CXX --mode=compile g++ -DHAVE_CONFIG_H -I. -I. -I. -I. -I. -ggdb -DBUILDING_HASHKIT -MT libhashkit/libhashkit_libhashkit_la-aes.lo -MD -MP -MF "libhashkit/.deps/libhashkit_libhashkit_la-aes.Tpo" -c -o libhashkit/libhashkit_libhashkit_la-aes.lo `test -f 'libhashkit/aes.cc' || echo './'`libhashkit/aes.cc; \ then mv -f "libhashkit/.deps/libhashkit_libhashkit_la-aes.Tpo" "libhashkit/.deps/libhashkit_libhashkit_la-aes.Plo"; else rm -f "libhashkit/.deps/libhashkit_libhashkit_la-aes.Tpo"; exit 1; fi ./libtool: line 866: X--tag=CXX: command not found ./libtool: line 899: libtool: ignoring unknown tag : command not found ./libtool: line 866: X--mode=compile: command not found ./libtool: line 1032: *** Warning: inferring the mode of operation is deprecated.: command not found ./libtool: line 1033: *** Future versions of Libtool will require --mode=MODE be specified.: command not found ./libtool: line 1176: Xg++: command not found ./libtool: line 1176: X-DHAVE_CONFIG_H: command not found ./libtool: line 1176: X-I.: command not found ./libtool: line 1176: X-I.: command not found ./libtool: line 1176: X-I.: command not found ./libtool: line 1176: X-I.: command not found ./libtool: line 1176: X-I.: command not found ./libtool: line 1176: X-ggdb: command not found ./libtool: line 1176: X-DBUILDING_HASHKIT: command not found ./libtool: line 1176: X-MT: command not found ./libtool: line 1176: Xlibhashkit/libhashkit_libhashkit_la-aes.lo: No such file or directory ./libtool: line 1176: X-MD: command not found ./libtool: line 1176: X-MP: command not found ./libtool: line 1176: X-MF: command not found ./libtool: line 1176: Xlibhashkit/.deps/libhashkit_libhashkit_la-aes.Tpo: No such file or directory ./libtool: line 1176: X-c: command not found ./libtool: line 1228: Xlibhashkit/libhashkit_libhashkit_la-aes.lo: No such file or directory ./libtool: line 1233: libtool: compile: cannot determine name of library object from `': command not found make[1]: *** [libhashkit/libhashkit_libhashkit_la-aes.lo] Error 1 make[1]: Leaving directory `/libmemcached' make: *** [all] Error 2 OUTPUT OF ./configure checking build system type... x86_64-unknown-linux-gnu checking host system type... x86_64-unknown-linux-gnu checking target system type... x86_64-unknown-linux-gnu checking for a BSD-compatible install... /usr/bin/install -c checking whether build environment is sane... yes checking for gawk... gawk checking whether make sets $(MAKE)... yes checking for style of include used by make... GNU checking for gcc... gcc checking whether the C compiler works... yes checking for C compiler default output file name... a.out checking for suffix of executables... checking whether we are cross compiling... no checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ISO C89... none needed checking dependency style of gcc... gcc3 checking dependency style of gcc... (cached) gcc3 checking how to run the C preprocessor... gcc -E checking for grep that handles long lines and -e... /bin/grep checking for egrep... /bin/grep -E checking for ANSI C header files... yes checking for sys/types.h... yes checking for sys/stat.h... yes checking for stdlib.h... yes checking for string.h... yes checking for memory.h... yes checking for strings.h... yes checking for inttypes.h... yes checking for stdint.h... yes checking for unistd.h... yes checking minix/config.h usability... no checking minix/config.h presence... no checking for minix/config.h... no checking whether it is safe to define __EXTENSIONS__... yes checking for isainfo... no checking for g++... g++ checking whether we are using the GNU C++ compiler... yes checking whether g++ accepts -g... yes checking dependency style of g++... gcc3 checking dependency style of g++... (cached) gcc3 checking whether gcc and cc understand -c and -o together... yes checking how to create a ustar tar archive... gnutar checking whether __SUNPRO_C is declared... no checking whether __ICC is declared... no checking "C Compiler version--yes"... "gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-52)" checking "C++ Compiler version"... "g++ (GCC) 4.1.2 20080704 (Red Hat 4.1.2-52)" checking whether time.h and sys/time.h may both be included... yes checking whether struct tm is in sys/time.h or time.h... time.h checking for size_t... yes checking for special C compiler options needed for large files... no checking for _FILE_OFFSET_BITS value needed for large files... no checking for library containing clock_gettime... -lrt checking sys/socket.h usability... yes checking sys/socket.h presence... yes checking for sys/socket.h... yes checking size of off_t... 8 checking size of size_t... 8 checking size of long long... 8 checking if time_t is unsigned... no checking for setsockopt... yes checking for bind... yes checking whether the compiler provides atomic builtins... yes checking assert.h usability... yes checking assert.h presence... yes checking for assert.h... yes checking whether to enable assertions... yes checking whether it is safe to use -fdiagnostics-show-option... yes checking whether it is safe to use -floop-parallelize-all... no checking whether it is safe to use -Wextra... yes checking whether it is safe to use -Wformat... yes checking whether it is safe to use -Wconversion... no checking whether it is safe to use -Wmissing-declarations from C++... no checking whether it is safe to use -Wframe-larger-than... no checking whether it is safe to use -Wlogical-op... no checking whether it is safe to use -Wredundant-decls from C++... yes checking whether it is safe to use -Wattributes from C++... no checking whether it is safe to use -Wno-attributes... no checking for perl... perl checking for dpkg-gensymbols... no checking for lcov... no checking for genhtml... no checking for sphinx-build... no checking for working -pipe... yes checking for bison... bison checking for flex... flex checking how to print strings... printf checking for a sed that does not truncate output... /bin/sed checking for fgrep... /bin/grep -F checking for ld used by gcc... /usr/bin/ld checking if the linker (/usr/bin/ld) is GNU ld... yes checking for BSD- or MS-compatible name lister (nm)... /usr/bin/nm -B checking the name lister (/usr/bin/nm -B) interface... BSD nm checking whether ln -s works... yes checking the maximum length of command line arguments... 98304 checking whether the shell understands some XSI constructs... yes checking whether the shell understands "+="... yes checking how to convert x86_64-unknown-linux-gnu file names to x86_64-unknown-linux-gnu format... func_convert_file_noop checking how to convert x86_64-unknown-linux-gnu file names to toolchain format... func_convert_file_noop checking for /usr/bin/ld option to reload object files... -r checking for objdump... objdump checking how to recognize dependent libraries... pass_all checking for dlltool... no checking how to associate runtime and link libraries... printf %s\n checking for ar... ar checking for archiver @FILE support... @ checking for strip... strip checking for ranlib... ranlib checking command to parse /usr/bin/nm -B output from gcc object... ok checking for sysroot... no checking for mt... no checking if : is a manifest tool... no checking for dlfcn.h... yes checking for objdir... .libs checking if gcc supports -fno-rtti -fno-exceptions... no checking for gcc option to produce PIC... -fPIC -DPIC checking if gcc PIC flag -fPIC -DPIC works... yes checking if gcc static flag -static works... yes checking if gcc supports -c -o file.o... yes checking if gcc supports -c -o file.o... (cached) yes checking whether the gcc linker (/usr/bin/ld -m elf_x86_64) supports shared libraries... yes checking whether -lc should be explicitly linked in... no checking dynamic linker characteristics... GNU/Linux ld.so checking how to hardcode library paths into programs... immediate checking whether stripping libraries is possible... yes checking if libtool supports shared libraries... yes checking whether to build shared libraries... yes checking whether to build static libraries... yes checking how to run the C++ preprocessor... g++ -E checking for ld used by g++... /usr/bin/ld -m elf_x86_64 checking if the linker (/usr/bin/ld -m elf_x86_64) is GNU ld... yes checking whether the g++ linker (/usr/bin/ld -m elf_x86_64) supports shared libraries... yes checking for g++ option to produce PIC... -fPIC -DPIC checking if g++ PIC flag -fPIC -DPIC works... yes checking if g++ static flag -static works... yes checking if g++ supports -c -o file.o... yes checking if g++ supports -c -o file.o... (cached) yes checking whether the g++ linker (/usr/bin/ld -m elf_x86_64) supports shared libraries... yes checking dynamic linker characteristics... (cached) GNU/Linux ld.so checking how to hardcode library paths into programs... immediate checking whether the -Werror option is usable... yes checking for simple visibility declarations... yes checking for ISO C++ 98 include files... checking whether memcached executable path has been provided... no checking for memcached... /usr/local/bin/memcached checking whether memcached_sasl executable path has been provided... no checking for memcached_sasl... no checking whether gearmand executable path has been provided... no checking for gearmand... no checking libgearman/gearmand.h usability... no checking libgearman/gearmand.h presence... no checking for libgearman/gearmand.h... no checking for library containing getopt_long... none required checking for library containing gethostbyname... none required checking for the pthreads library -lpthreads... no checking whether pthreads work without any flags... yes checking for joinable pthread attribute... PTHREAD_CREATE_JOINABLE checking if more special flags are required for pthreads... no checking for PTHREAD_PRIO_INHERIT... yes checking the location of cstdint... configure: WARNING: Could not find a cstdint header. <stdint.h> checking the location of cinttypes... configure: WARNING: Could not find a cinttypes header. <inttypes.h> checking whether byte ordering is bigendian... no checking for htonll... no checking for working SO_SNDTIMEO... yes checking for working SO_RCVTIMEO... yes checking for supported struct padding... yes checking for alarm... yes checking for dup2... yes checking for getline... yes checking for gettimeofday... yes checking for memchr... yes checking for memmove... yes checking for memset... yes checking for pipe2... no checking for select... yes checking for setenv... yes checking for socket... yes checking for sqrt... yes checking for strcasecmp... yes checking for strchr... yes checking for strdup... yes checking for strerror... yes checking for strtol... yes checking for strtoul... yes checking for strtoull... yes checking arpa/inet.h usability... yes checking arpa/inet.h presence... yes checking for arpa/inet.h... yes checking fcntl.h usability... yes checking fcntl.h presence... yes checking for fcntl.h... yes checking libintl.h usability... yes checking libintl.h presence... yes checking for libintl.h... yes checking limits.h usability... yes checking limits.h presence... yes checking for limits.h... yes checking malloc.h usability... yes checking malloc.h presence... yes checking for malloc.h... yes checking netdb.h usability... yes checking netdb.h presence... yes checking for netdb.h... yes checking netinet/in.h usability... yes checking netinet/in.h presence... yes checking for netinet/in.h... yes checking stddef.h usability... yes checking stddef.h presence... yes checking for stddef.h... yes checking sys/time.h usability... yes checking sys/time.h presence... yes checking for sys/time.h... yes checking execinfo.h usability... yes checking execinfo.h presence... yes checking for execinfo.h... yes checking cxxabi.h usability... yes checking cxxabi.h presence... yes checking for cxxabi.h... yes checking sys/sysctl.h usability... yes checking sys/sysctl.h presence... yes checking for sys/sysctl.h... yes checking umem.h usability... no checking umem.h presence... no checking for umem.h... no checking for C++ compiler vendor... gnu checking for working alloca.h... yes checking for alloca... yes checking for error_at_line... yes checking for pid_t... yes checking vfork.h usability... no checking vfork.h presence... no checking for vfork.h... no checking for fork... yes checking for vfork... yes checking for working fork... yes checking for working vfork... (cached) yes checking for stdlib.h... (cached) yes checking for GNU libc compatible malloc... yes checking for stdlib.h... (cached) yes checking for GNU libc compatible realloc... yes checking whether strerror_r is declared... yes checking for strerror_r... yes checking whether strerror_r returns char *... yes checking for stdbool.h that conforms to C99... yes checking for _Bool... no checking for int16_t... yes checking for int32_t... yes checking for int64_t... yes checking for int8_t... yes checking for off_t... yes checking for pid_t... (cached) yes checking for ssize_t... yes checking for uint16_t... yes checking for uint32_t... yes checking for uint64_t... yes checking for uint8_t... yes checking whether byte ordering is bigendian... (cached) no checking for an ANSI C-conforming const... yes checking for inline... inline checking for working volatile... yes checking for C/C++ restrict keyword... __restrict checking whether the compiler supports GCC C++ ABI name demangling... yes checking sasl/sasl.h usability... no checking sasl/sasl.h presence... no checking for sasl/sasl.h... no checking uuid/uuid.h usability... yes checking uuid/uuid.h presence... yes checking for uuid/uuid.h... yes checking for main in -luuid... yes checking for clock_gettime in -lrt... yes checking for floor in -lm... yes checking for sigignore... yes checking atomic.h usability... no checking atomic.h presence... no checking for atomic.h... no checking for setppriv... no checking for winsock2.h... no checking for poll.h... yes checking for sys/wait.h... yes checking for fnmatch.h... yes checking for MSG_NOSIGNAL... yes checking for MSG_DONTWAIT... yes checking for MSG_MORE... yes checking event.h usability... yes checking event.h presence... yes checking for event.h... yes checking for main in -levent... yes checking for endianness... little configure: creating ./config.status config.status: creating Makefile config.status: creating docs/conf.py config.status: creating libhashkit-1.0/configure.h config.status: creating libmemcached-1.0/configure.h config.status: creating libmemcached-1.2/configure.h config.status: creating libmemcached-2.0/configure.h config.status: creating support/libmemcached.pc config.status: creating support/libmemcached.spec config.status: creating support/libmemcached-fc.spec config.status: creating libtest/version.h config.status: creating config.h config.status: config.h is unchanged config.status: executing depfiles commands config.status: executing libtool commands --- Configuration summary for libmemcached version 1.0.6 * Installation prefix: /usr/local * System type: unknown-linux-gnu * Host CPU: x86_64 * C Compiler: gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-52) * Assertions enabled: yes * Debug enabled: no * Warnings as failure: no * SASL support: --- anyone knows how to solve this ?

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