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• Memory Efficient Windows SOA Server

  - by Antony Reynolds

  Installing a Memory Efficient SOA Suite 11.1.1.6 on Windows Server Well 11.1.1.6 is now available for download so I thought I would build a Windows Server environment to run it.  I will minimize the memory footprint of the installation by putting all functionality into the Admin Server of the SOA Suite domain. Required Software 64-bit JDK SOA Suite If you want 64-bit then choose “Generic” rather than “Microsoft Windows 32bit JVM” or “Linux 32bit JVM” This has links to all the required software. If you choose “Generic” then the Repository Creation Utility link does not show, you still need this so change the platform to “Microsoft Windows 32bit JVM” or “Linux 32bit JVM” to get the software. Similarly if you need a database then you need to change the platform to get the link to XE for Windows or Linux. If possible I recommend installing a 64-bit JDK as this allows you to assign more memory to individual JVMs. Windows XE will work, but it is better if you can use a full Oracle database because of the limitations on XE that sometimes cause it to run out of space with large or multiple SOA deployments. Installation Steps The following flow chart outlines the steps required in installing and configuring SOA Suite. The steps in the diagram are explained below. 64-bit? Is a 64-bit installation required?  The Windows & Linux installers will install 32-bit versions of the Sun JDK and JRockit.  A separate JDK must be installed for 64-bit. Install 64-bit JDK The 64-bit JDK can be either Hotspot or JRockit.  You can choose either JDK 1.7 or 1.6. Install WebLogic If you are using 64-bit then install WebLogic using “java –jar wls1036_generic.jar”.  Make sure you include Coherence in the installation, the easiest way to do this is to accept the “Typical” installation. SOA Suite Required? If you are not installing SOA Suite then you can jump straight ahead and create a WebLogic domain. Install SOA Suite Run the SOA Suite installer and point it at the existing Middleware Home created for WebLogic.  Note to run the SOA installer on Windows the user must have admin privileges.  I also found that on Windows Server 2008R2 I had to start the installer from a command prompt with administrative privileges, granting it privileges when it ran caused it to ignore the jreLoc parameter. Database Available? Do you have access to a database into which you can install the SOA schema.  SOA Suite requires access to an Oracle database (it is supported on other databases but I would always use an oracle database). Install Database I use an 11gR2 Oracle database to avoid XE limitations.  Make sure that you set the database character set to be unicode (AL32UTF8).  I also disabled the new security settings because they get in the way for a developer database.  Don’t forget to check that number of processes is at least 150 and number of sessions is not set, or is set to at least 200 (in the DB init parameters). Run RCU The SOA Suite database schemas are created by running the Repository Creation Utility.  Install the “SOA and BPM Infrastructure” component to support SOA Suite.  If you keep the schema prefix as “DEV” then the config wizard is easier to complete. Run Config Wizard The Config wizard creates the domain which hosts the WebLogic server instances.  To get a minimum footprint SOA installation choose the “Oracle Enterprise Manager” and “Oracle SOA Suite for developers” products.  All other required products will be automatically selected. The “for developers” installs target the appropriate components at the AdminServer rather than creating a separate managed server to house them.  This reduces the number of JVMs required to run the system and hence the amount of memory required.  This is not suitable for anything other than a developer environment as it mixes the admin and runtime functions together in a single server.  It also takes a long time to load all the required modules, making start up a slow process. If it exists I would recommend running the config wizard found in the “oracle_common/common/bin” directory under the middleware home.  This should have access to all the templates, including SOA. If you also want to run BAM in the same JVM as everything else then you need to “Select Optional Configuration” for “Managed Servers, Clusters and Machines”. To target BAM at the AdminServer delete the “bam_server1” managed server that is created by default.  This will result in BAM being targeted at the AdminServer. Installation Issues I had a few problems when I came to test everything in my mega-JVM. Following applications were not targeted and so I needed to target them at the AdminServer: b2bui composer Healthcare UI FMW Welcome Page Application (11.1.0.0.0) How Memory Efficient is It? On a Windows 2008R2 Server running under VirtualBox I was able to bring up both the 11gR2 database and SOA/BPM/BAM in 3G memory.  I allocated a minimum 512M to the PermGen and a minimum of 1.5G for the heap.  The setting from setSOADomainEnv are shown below: set DEFAULT_MEM_ARGS=-Xms1536m -Xmx2048m set PORT_MEM_ARGS=-Xms1536m -Xmx2048m set DEFAULT_MEM_ARGS=%DEFAULT_MEM_ARGS% -XX:PermSize=512m -XX:MaxPermSize=768m set PORT_MEM_ARGS=%PORT_MEM_ARGS% -XX:PermSize=512m -XX:MaxPermSize=768m I arrived at these numbers by monitoring JVM memory usage in JConsole. Task Manager showed total system memory usage at 2.9G – just below the 3G I allocated to the VM. Performance is not stellar but it runs and I could run JDeveloper alongside it on my 8G laptop, so in that sense it was a result!

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• What Counts For a DBA: Simplicity

  - by Louis Davidson

  Too many computer processes do an apparently simple task in a bizarrely complex way. They remind me of this strip by one of my favorite artists: Rube Goldberg. In order to keep the boss from knowing one was late, a process is devised whereby the cuckoo clock kisses a live cuckoo bird, who then pulls a string, which triggers a hat flinging, which in turn lands on a rod that removes a typewriter cover…and so on. We rely on creating automated processes to keep on top of tasks. DBAs have a lot of tasks to perform: backups, performance tuning, data movement, system monitoring, and of course, avoiding being noticed.  Every day, there are many steps to perform to maintain the database infrastructure, including: checking physical structures, re-indexing tables where needed, backing up the databases, checking those backups, running the ETL, and preparing the daily reports and yes, all of these processes have to complete before you can call it a day, and probably before many others have started that same day. Some of these tasks are just naturally complicated on their own. Other tasks become complicated because the database architecture is excessively rigid, and we often discover during “production testing” that certain processes need to be changed because the written requirements barely resembled the actual customer requirements.   Then, with no time to change that rigid structure, we are forced to heap layer upon layer of code onto the problematic processes. Instead of a slight table change and a new index, we end up with 4 new ETL processes, 20 temp tables, 30 extra queries, and 1000 lines of SQL code.  Report writers then need to build reports and make magical numbers appear from those toxic data structures that are overly complex and probably filled with inconsistent data. What starts out as a collection of fairly simple tasks turns into a Goldbergian nightmare of daily processes that are likely to cause your dinner to be interrupted by the smartphone doing the vibration dance that signifies trouble at the mill. So what to do? Well, if it is at all possible, simplify the problem by either going into the code and refactoring the complex code to simple, or taking all of the processes and simplifying them into small, independent, easily-tested steps.  The former approach usually requires an agreement on changing underlying structures that requires countless mind-numbing meetings; while the latter can generally be done to any complex process without the same frustration or anger, though it will still leave you with lots of steps to complete, the ability to test each step independently will definitely increase the quality of the overall process (and with each step reporting status back, finding an actual problem within the process will be definitely less unpleasant.) We all know the principle behind simplifying a sequence of processes because we learned it in math classes in our early years of attending school, starting with elementary school. In my 4 years (ok, 9 years) of undergraduate work, I remember pretty much one thing from my many math classes that I apply daily to my career as a data architect, data programmer, and as an occasional indentured DBA: “show your work”. This process of showing your work was my first lesson in simplification. Each step in the process was in fact, far simpler than the entire process.  When you were working an equation that took both sides of 4 sheets of paper, showing your work was important because the teacher could see every step, judge it, and mark it accordingly.  So often I would make an error in the first few lines of a problem which meant that the rest of the work was actually moving me closer to a very wrong answer, no matter how correct the math was in the subsequent steps. Yet, when I got my grade back, I would sometimes be pleasantly surprised. I passed, yet missed every problem on the test. But why? While I got the fact that 1+1=2 wrong in every problem, the teacher could see that I was using the right process. In a computer process, the process is very similar. We take complex processes, show our work by storing intermediate values, and test each step independently. When a process has 100 steps, each step becomes a simple step that is tested and verified, such that there will be 100 places where data is stored, validated, and can be checked off as complete. If you get step 1 of 100 wrong, you can fix it and be confident (that if you did your job of testing the other steps better than the one you had to repair,) that the rest of the process works. If you have 100 steps, and store the state of the process exactly once, the resulting testable chunk of code will be far more complex and finding the error will require checking all 100 steps as one, and usually it would be easier to find a specific needle in a stack of similarly shaped needles.  The goal is to strive for simplicity either in the solution, or at least by simplifying every process down to as many, independent, testable, simple tasks as possible.  For the tasks that really can’t be done completely independently, minimally take those tasks and break them down into simpler steps that can be tested independently.  Like working out division problems longhand, have each step of the larger problem verified and tested.

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• The Sound of Two Toilets Flushing: Constructive Criticism for Virgin Atlantic Complaints Department

  - by Geertjan

  I recently had the experience of flying from London to Johannesburg and back with Virgin Atlantic. The good news was that it was the cheapest flight available and that the take off and landing were absolutely perfect. Hence I really have no reason to complain. Instead, I'd like to offer some constructive criticism which hopefully Richard Branson will find sometime while googling his name. Or maybe someone from the Virgin Atlantic Complaints Department will find it, whatever, just want to put this information out there. Arrangement of restroom facilities. Maybe next time you design an airplane, consider not putting your toilets at a right angle right next to your rows of seats. Being able to reach, without even needing to stretch your arm, from your seat to close, yet again, a toilet door that someone, someone obviously sitting very far from the toilets, carelessly forgot to close is not an indicator of quality interior design. Have you noticed how all other airplanes have their toilets in a cubicle separated from the rows of seats? On those airplanes, people sitting in the seats near the toilets are not constantly being woken up throughout the night whenever someone enters/exits the toilet, whenever the light in the toilet is suddenly switched on, and whenever one of the toilets flushes. Bonus points for Virgin Atlantic passengers in the seats adjoining the toilets is when multiple toilets are flushed simultaneously and multiple passengers enter/exit them at the same time, a bit like an unasked for low budget musical of suddenly illuminated grumpy people in crumpled clothes. What joy that brings at 3 AM is hard to describe. Seats with extra leg room. You know how other airplanes have the seats with the extra leg room? You know what those seats tend to have? Extra leg room. It's really interesting how Virgin Atlantic's seats with extra leg room actually have no extra leg room at all. It should have been a give away, the fact that these special seats are found in the same rows as the standard seats, rather than on the cusp of real glory which is where most airlines put their extra leg room seats, with the only actual difference being that they have a slightly different color. Had you called them "seats with a different color" (i.e., almost not quite green, rather than something vaguely hinting at blue), at least I'd have known what I was getting. Picture the joy at 3 AM, rudely awakened from nightmarish slumber, partly grateful to have been released from a grayish dream of faceless zombies resembling one or two of those in a recent toilet line, by multiple adjoining toilets flushing simultaneously, while you're sitting in a seat with extra leg room that has exactly as much leg room as the seats in neighboring rows. You then have a choice of things to be sincerely annoyed about. Food from the '80's. In the '80's, airplane food came in soggy containers and even breakfast, the most important meal of the day, was a sad heap of vaguely gray colors. The culinary highlight tended to be a squashed tomato, which must have been mashed to a pulp with a brick prior to being regurgitated by a small furry animal, and there was also always a piece of immensely horrid pumpkin, as well as a slice of spongy something you'd never seen before. Sausages and mash at 6 AM on an airplane was always a heavy lump of horribleness. Thankfully, all airlines throughout the world changed from this puke inducing strategy around 1987 sometime. Not Virgin Atlantic, of course. The fatty sausages and mash are still there, bringing you flashbacks to Duran Duran, which is what you were listening to (on your walkman) the last time you saw it in an airplane. Even the golden oldie "squashed tomato attached by slime to three wet peas" is on the menu. How wonderful to have all this in a cramped seat with a long row of early morning bleariness lined up for the toilets, right at your side, bumping into your elbow, groggily, one by one, one after another, more and more, fumble-open-door-silence-flush-fumble-open-door, and on and on, while you tentatively push your fork through a soggy pile of colorless mush, fighting the urge to throw up on the stinky socks of whatever nightmarish zombie is bumping into your elbow at the time. But, then again, the plane landed without a hitch, in fact, extremely smoothly, so I'm certainly not blaming the pilots.

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• Profiling Startup Of VS2012 &ndash; YourKit Profiler

  - by Alois Kraus

  The YourKit (v7.0.5) profiler is interesting in terms of price (79€ single place license, 409€ + 1 year support and upgrades) and feature set. You do get a performance and memory profiler in one package for which you normally need also to pay extra from the other vendors. As an interesting side note the profiler UI is written in Java because they do also sell Java profilers with the same feature set. To get all methods of a VS startup you need first to configure it to include System* in the profiled methods and you need to configure * to measure wall clock time. By default it does record only CPU times which allows you to optimize CPU hungry operations. But you will never see a Thread.Sleep(10000) in the profiler blocking the UI in this mode. It can profile as all others processes started from within the profiler but it can also profile the next or all started processes. As usual it can profile in sampling and tracing mode. But since it is a memory profiler as well it does by default also record all object allocations > 1MB. With allocation recording enabled VS2012 did crash but without allocation recording there were no problems. The CPU tab contains the time line of the application and when you click in the graph you the call stacks of all threads at this time. This is really a nice feature. When you select a time region you the CPU Usage estimation for this time window. I have seen many applications consuming 100% CPU only because they did create garbage like crazy. For this is the Garbage Collection tab interesting in conjunction with a time range. This view is like the CPU table only that the CPU graph (green) is missing. All relevant information except for GCs/s is already visible in the CPU tab. Very handy to pinpoint excessive GC or CPU bound issues. The Threads tab does show the thread names and their lifetime. This is useful to see thread interactions or which thread is hottest in terms of CPU consumption. On the CPU tab the call tree does exist in a merged and thread specific view. When you click on a method you get below a list of all called methods. There you can sort for methods with a high own time which are worth optimizing. In the Method List you can select which scope you want to see. Back Traces are the methods which did call you. Callees ist the list of methods called directly or indirectly by your method as a flat list. This is not a call stack but still very useful to see which methods were slow so you can see the “root” cause quite quickly without the need to click trough long call stacks. The last view Merged Calles is a call stacked view of the previous view. This does help a lot to understand did call each method at run time. You would get the same view with a debugger for one call invocation but here you get the full statistics (invocation count) as well. Since YourKit is also a memory profiler you can directly see which objects you have on your managed heap and which objects do hold most of your precious memory. You can in in the Object Explorer view also examine the contents of your objects (strings or whatsoever) to get a better understanding which objects where potentially allocating this stuff.   YourKit is a very easy to use combined memory and performance profiler in one product. The unbeatable single license price makes it very attractive to straightly buy it. Although it is a Java UI it is very responsive and the memory consumption is considerably lower compared to dotTrace and ANTS profiler. What I do really like is to start the YourKit ui and then start the processes I want to profile as usual. There is no need to alter your own application code to be able to inject a profiler into your new started processes. For performance and memory profiling you can simply select the process you want to investigate from the list of started processes. That's the way I like to use profilers. Just get out of the way and let the application run without any special preparations.   Next: Telerik JustTrace

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• Profiling NetBeans 7.0 Beta 2 and Reporting Problems

  - by christopher.jones

  With NetBeans 7.0 recently going into Beta 2 phase, now is the time to test it out properly and report issues. The development team has been squashing bugs, including memory issues with the PHP bundle.There are some great new PHP related features in NetBeans 7.0, so you know you want to try it out.If you identify something wrong with NetBeans, please report it following the guidelines http://wiki.netbeans.org/IssueReportingGuidelinesDepending on the issues, data to attach to the report is mentioned on: http://wiki.netbeans.org/FaqLogMessagesFile and http://wiki.netbeans.org/FaqProfileMeNowIf you have a memory issue then a memory dump would also be useful. Run the jmap tool for this. There is some background information on http://wiki.netbeans.org/FaqMemoryDump. Here's how I used it.First I set my environment to match the JDK used by NetBeans. In my case I am using a nightly build so the JDK is in the configuration file under $HOME/netbeans-dev-201102210501:$ egrep netbeans_jdkhome $HOME/netbeans-dev-201102210501/etc/netbeans.conf netbeans_jdkhome="/home/cjones/src/jdk1.6.0_24" $ export JAVA_HOME=/home/cjones/src/jdk1.6.0_24 $ export PATH=$JAVA_HOME/bin:$PATH Next, I found the correct process number to examine:$ ps -ef | egrep 'netbeans|jdk'cjones   23230     1  0 16:07 ?        00:00:00 /bin/bash /home/cjones/netbeans-cjones   23438 23230  2 16:07 ?        00:00:09 /home/cjones/src/jdk1.6.0_24/binFinally I used the parent JDK process as the jmap argument:$ jmap -histo:live 23438 num     #instances         #bytes  class name----------------------------------------------   1:         12075        9028656  [I   2:         49535        6581920  <constMethodKlass>   3:         49535        3964128  <methodKlass>   4:         80256        3840776  <symbolKlass>   5:         36093        3635336  [C   6:          5095        3341312  <constantPoolKlass>   7:          5095        2486016  <instanceKlassKlass>   8:          4325        1961432  <constantPoolCacheKlass>   9:         18729        1763976  [B  10:         59952        1438848  java.util.HashMap$Entry  . . .This histogram memory report will help identify the kind of memory issues you are seeing. It may not be as complete as an often tens of megabyte jmap -dump:live,file=/tmp/nbheap.log 23438 heap dump, but is much more easily attached to a bug report.If you want to keep up to date with NetBeans, nightly builds are at: http://bits.netbeans.org/download/trunk/nightly/latest/zip/

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• Deduping your redundancies

  - by nospam(at)example.com (Joerg Moellenkamp)

  Robin Harris of Storagemojo pointed to an interesting article about about deduplication and it's impact to the resiliency of your data against data corruption on ACM Queue. The problem in short: A considerable number of filesystems store important metadata at multiple locations. For example the ZFS rootblock is copied to three locations. Other filesystems have similar provisions to protect their metadata. However you can easily proof, that the rootblock pointer in the uberblock of ZFS for example is pointing to blocks with absolutely equal content in all three locatition (with zdb -uu and zdb -r). It has to be that way, because they are protected by the same checksum. A number of devices offer block level dedup, either as an option or as part of their inner workings. However when you store three identical blocks on them and the devices does block level dedup internally, the device may just deduplicated your redundant metadata to a block stored just once that is stored on the non-voilatile storage. When this block is corrupted, you have essentially three corrupted copies. Three hit with one bullet. This is indeed an interesting problem: A device doing deduplication doesn't know if a block is important or just a datablock. This is the reason why I like deduplication like it's done in ZFS. It's an integrated part and so important parts don't get deduplicated away. A disk accessed by a block level interface doesn't know anything about the importance of a block. A metadata block is nothing different to it's inner mechanism than a normal data block because there is no way to tell that this is important and that those redundancies aren't allowed to fall prey to some clever deduplication mechanism. Robin talks about this in regard of the Sandforce disk controllers who use a kind of dedup to reduce some of the nasty effects of writing data to flash, but the problem is much broader. However this is relevant whenever you are using a device with block level deduplication. It's just the point that you have to activate it for most implementation by command, whereas certain devices do this by default or by design and you don't know about it. However I'm not perfectly sure about that ? given that storage administration and server administration are often different groups with different business objectives I would ask your storage guys if they have activated dedup without telling somebody elase on their boxes in order to speak less often with the storage sales rep. The problem is even more interesting with ZFS. You may use ditto blocks to protect important data to store multiple copies of data in the pool to increase redundancy, even when your pool just consists out of one disk or just a striped set of disk. However when your device is doing dedup internally it may remove your redundancy before it hits the nonvolatile storage. You've won nothing. Just spend your disk quota on the the LUNs in the SAN and you make your disk admin happy because of the good dedup ratio However you can just fall in this specific "deduped ditto block"trap when your pool just consists out of a single device, because ZFS writes ditto blocks on different disks, when there is more than just one disk. Yet another reason why you should spend some extra-thought when putting your zpool on a single LUN, especially when the LUN is sliced and dices out of a large heap of storage devices by a storage controller. However I have one problem with the articles and their specific mention of ZFS: You can just hit by this problem when you are using the deduplicating device for the pool. However in the specifically mentioned case of SSD this isn't the usecase. Most implementations of SSD in conjunction with ZFS are hybrid storage pools and so rotating rust disk is used as pool and SSD are used as L2ARC/sZIL. And there it simply doesn't matter: When you really have to resort to the sZIL (your system went down, it doesn't matter of one block or several blocks are corrupt, you have to fail back to the last known good transaction group the device. On the other side, when a block in L2ARC is corrupt, you simply read it from the pool and in HSP implementations this is the already mentioned rust. In conjunction with ZFS this is more interesting when using a storage array, that is capable to do dedup and where you use LUNs for your pool. However as mentioned before, on those devices it's a user made decision to do so, and so it's less probable that you deduplicating your redundancies. Other filesystems lacking acapability similar to hybrid storage pools are more "haunted" by this problem of SSD using dedup-like mechanisms internally, because those filesystem really store the data on the the SSD instead of using it just as accelerating devices. However at the end Robin is correct: It's jet another point why protecting your data by creating redundancies by dispersing it several disks (by mirror or parity RAIDs) is really important. No dedup mechanism inside a device can dedup away your redundancy when you write it to a totally different and indepenent device.

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• NetBeans not liking libraries in lib-src

  - by DJTripleThreat

  I'm working on a project with a group that is using Eclipse, but I'm using Netbeans. Up until today this wasn't an issue. When updating from the repo they have added some source code as a library under a directory called /lib-src. When I try to compile the code I get an error that it can't find certain packages... these are the packages under /lib-src. Using NetBeans I can add the library as a folder so now the references to those packages are happy. However, I'm getting this new error when compiling: UNEXPECTED TOP-LEVEL ERROR: java.lang.OutOfMemoryError: Java heap space at java.util.HashMap.addEntry(HashMap.java:753) at java.util.HashMap.put(HashMap.java:385) at com.android.dx.dex.file.ClassDataItem.addStaticField(ClassDataItem.java:134) at com.android.dx.dex.file.ClassDefItem.addStaticField(ClassDefItem.java:280) at com.android.dx.dex.cf.CfTranslator.processFields(CfTranslator.java:159) at com.android.dx.dex.cf.CfTranslator.translate0(CfTranslator.java:130) at com.android.dx.dex.cf.CfTranslator.translate(CfTranslator.java:85) at com.android.dx.command.dexer.Main.processClass(Main.java:297) at com.android.dx.command.dexer.Main.processFileBytes(Main.java:276) at com.android.dx.command.dexer.Main.access$100(Main.java:56) at com.android.dx.command.dexer.Main$1.processFileBytes(Main.java:228) at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:134) at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:190) at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:122) at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:190) at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:122) at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:190) at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:122) at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:190) at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:122) at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:190) at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:122) at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:190) at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:122) at com.android.dx.cf.direct.ClassPathOpener.processDirectory(ClassPathOpener.java:190) at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:122) at com.android.dx.cf.direct.ClassPathOpener.process(ClassPathOpener.java:108) at com.android.dx.command.dexer.Main.processOne(Main.java:245) at com.android.dx.command.dexer.Main.processAllFiles(Main.java:183) at com.android.dx.command.dexer.Main.run(Main.java:139) at com.android.dx.command.dexer.Main.main(Main.java:120) at com.android.dx.command.Main.main(Main.java:87) /home/aaron/NetBeansProjects/xbmc-remote/nbproject/build-impl.xml:411: exec returned: 3 BUILD FAILED (total time: 1 minute 25 seconds) I can include the build-impl.xml file if you need it, but I don't think that is main issue. Any ideas?

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• Mocking using boost::shared_ptr and AMOP

  - by Edison Gustavo Muenz

  Hi, I'm trying to write mocks using amop. I'm using Visual Studio 2008. I have this interface class: struct Interface { virtual void Activate() = 0; }; and this other class which receives pointers to this Interface, like this: struct UserOfInterface { void execute(Interface* iface) { iface->Activate(); } }; So I try to write some testing code like this: amop::TMockObject<Interface> mock; mock.Method(&Interface::Activate).Count(1); UserOfInterface user; user.execute((Interface*)mock); mock.Verifiy(); It works! So far so good, but what I really want is a boost::shared_ptr in the execute() method, so I write this: struct UserOfInterface { void execute(boost::shared_ptr<Interface> iface) { iface->Activate(); } }; How should the test code be now? I tried some things, like: amop::TMockObject<Interface> mock; mock.Method(&Interface::Activate).Count(1); UserOfInterface user; boost::shared_ptr<Interface> mockAsPtr((Interface*)mock); user.execute(mockAsPtr); mock.Verifiy(); It compiles, but obviously crashes, since at the end of the scope the variable 'mock' gets double destroyed (because of the stack variable 'mock' and the shared_ptr). I also tried to create the 'mock' variable on the heap: amop::TMockObject<Interface>* mock(new amop::TMockObject<Interface>); mock->Method(&Interface::Activate).Count(1); UserOfInterface user; boost::shared_ptr<Interface> mockAsPtr((Interface*)*mock); user.execute(mockAsPtr); mock->Verifiy(); But it doesn't work, somehow it enters an infinite loop, before I had a problem with boost not finding the destructor for the mocked object when the shared_ptr tried to delete the object. Has anyone used amop with boost::shared_ptr successfully?

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• Stack Overflow problem in a recursive program in C

  - by Adi

  Hi all, I am getting a stack overflow in one of the recursive functions i am running.. Here is the code.. void* buddyMalloc(int req_size) { // Do something here return buddy_findout(original_index,req_size); // This is the recursive call } void *buddy_findout(int current_index,int req_size) { char *selected = NULL; if(front!=NULL) { if(current_index==original_index) { // Do something here return selected; } else { // Do Something here return buddy_findout(current_index+1,req_size); } } else { return buddy_findout(current_index-1,req_size); } } Consider the initial value of index to be 4. and it first do index-1 till it reaches 0 index. and then it comes back to index 4 by incrementing..This is wht i want to implement. But it gives a stack overflow with memory map in the command prompt : Here is the output from my shell : * glibc detected * ./473_mem: free(): invalid pointer: 0x00c274c0 * ======= Backtrace: ========= /lib/tls/i686/cmov/libc.so.6[0xb50ff1] /lib/tls/i686/cmov/libc.so.6[0xb526f2] /lib/tls/i686/cmov/libc.so.6(cfree+0x6d)[0xb557cd] ./473_mem[0x8048b44] ./473_mem[0x8048b74] ./473_mem[0x8048b74] ./473_mem[0x8048944] ./473_mem[0x8048c87] ./473_mem[0x8048d31] ./473_mem[0x8048f79] /lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xe6)[0xafcb56] ./473_mem[0x8048671] ======= Memory map: ======== 0017c000-00198000 r-xp 00000000 08:01 5224 /lib/libgcc_s.so.1 00198000-00199000 r--p 0001b000 08:01 5224 /lib/libgcc_s.so.1 00199000-0019a000 rw-p 0001c000 08:01 5224 /lib/libgcc_s.so.1 00260000-00284000 r-xp 00000000 08:01 1927 /lib/tls/i686/cmov/libm-2.10.1.so 00284000-00285000 r--p 00023000 08:01 1927 /lib/tls/i686/cmov/libm-2.10.1.so 00285000-00286000 rw-p 00024000 08:01 1927 /lib/tls/i686/cmov/libm-2.10.1.so 006cd000-006e8000 r-xp 00000000 08:01 6662 /lib/ld-2.10.1.so 006e8000-006e9000 r--p 0001a000 08:01 6662 /lib/ld-2.10.1.so 006e9000-006ea000 rw-p 0001b000 08:01 6662 /lib/ld-2.10.1.so 00aa9000-00aaa000 r-xp 00000000 00:00 0 [vdso] 00ae6000-00c24000 r-xp 00000000 08:01 1900 /lib/tls/i686/cmov/libc-2.10.1.so 00c24000-00c25000 ---p 0013e000 08:01 1900 /lib/tls/i686/cmov/libc-2.10.1.so 00c25000-00c27000 r--p 0013e000 08:01 1900 /lib/tls/i686/cmov/libc-2.10.1.so 00c27000-00c28000 rw-p 00140000 08:01 1900 /lib/tls/i686/cmov/libc-2.10.1.so 00c28000-00c2b000 rw-p 00000000 00:00 0 08048000-0804a000 r-xp 00000000 00:14 2176 /media/windows-share/OS/Project2/473_mem 0804a000-0804b000 r--p 00001000 00:14 2176 /media/windows-share/OS/Project2/473_mem 0804b000-0804c000 rw-p 00002000 00:14 2176 /media/windows-share/OS/Project2/473_mem 08483000-084a4000 rw-p 00000000 00:00 0 [heap] b7600000-b7621000 rw-p 00000000 00:00 0 b7621000-b7700000 ---p 00000000 00:00 0 b7716000-b7819000 rw-p 00000000 00:00 0 b7827000-b782a000 rw-p 00000000 00:00 0 bfb96000-bfbab000 rw-p 00000000 00:00 0 [stack] Aborted Thanks in advance adi

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• Windows forms application blocks after station lock

  - by Silviu

  We're having a serious issue at work. We've discovered that after the station where the client was running is locked/unlocked the client is blocked. No repaint. So the UI thread is blocked with something. Looking at the callstack of the UI thread (thread 0) using windbg we see that a UserPreferenceChanged event gets raised. It is marshalled through a WindowsFormsSynchronizationContext using it's controlToSend field to the UI. It gets blocked by a call to the marshalling control. The method called is MarshaledInvoke it builds a ThreadMethodEntry entry = new ThreadMethodEntry(caller, method, args, synchronous, executionContext); This entry is supposed to do the magic. The call is a synchronous call and because of that (still in the MarshaledInvoke of the Control class) the wait call is reached: if (!entry.IsCompleted) { this.WaitForWaitHandle(entry.AsyncWaitHandle); } The last thing that i can see on the stack is the WaitOne called on the previously mentioned AsyncWaitHandle. This is very annoying because having just the callstack of the runtime and not one of our methods being invoked we cannot really point to a bug in our code. I might be wrong, but I'm guessing that the marshaling control is not "marshaling" to the ui thread. But another one...i don't really know which one because the other threads are being used by us and are blocked...maybe this is the issue. But none of the other threads are running a message loop. This is very annoying. We had some issues in the past with marshaling controls to the right ui thread. That is because the first form that is constructed is a splash form. Which is not the main form. We used to use the main form to marshal call to the ui thread. But from time to time some calls would go to a non ui thread and some grids would broke with a big red X on them. I fixed this by creating a specific class: public class WindowsFormsSynchronizer { private static readonly WindowsFormsSynchronizationContext = new WindowsFormsSynchronizationContext(); //Methods are following that would build the same interface of the synchronization context. } This class gets build as one of the first objects in the first form being constructed. We've noticed some other strange thing. Looking at the heap there are 7 WindowsFormsSynchronizationContext objects. 6 of these have the same instance of controlToSend, and the other one has some different instance of controlToSend. This last one is the one that should marshal the calls to the UI. I don't have any other idea...maybe some of you guys had this same issue?

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• Handwritten linked list is segfaulting and I don't understand why

  - by Born2Smile

  Hi I was working on a bit of fun, making an interface to run gnuplot from within c++, and for some reason the my linked list implementation fails. The code below fails on the line plots-append(&plot). Stepping through the code I discovered that for some reason the destructor ~John() is called immediately after the constructor John(), and I cannot seem to figure out why. The code included below is a stripped down version operating only on Plot*. Originally I made the linked list as a template class. And it worked fine as ll<int and ll<char* but for some reason it fails as ll<Plot*. Could youp please help me figure out why it fails? and perhaps help me understand how to make it work? In advance: Thanks a heap! //B2S #include <string.h class Plot{ char title[80]; public: Plot(){ } }; class Link{ Plot* element; Link* next; Link* prev; friend class ll; }; class ll{ Link* head; Link* tail; public: ll(){ head = tail = new Link(); head-prev = tail-prev = head-next = tail-next = head; } ~ll(){ while (head!=tail){ tail = tail-prev; delete tail-next; } delete head; } void append(Plot* element){ tail-element = element; tail-next = new Link(); tail-next-prev = tail; tail-next = tail; } }; class John{ ll* plots; public: John(){ plots= new ll(); } ~John(){ delete plots; } John(Plot* plot){ John(); plots-append(plot); } }; int main(){ Plot p; John k(&p); }

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• Seg Fault when using std::string on an embedded Linux platform

  - by Brad

  Hi, I have been working for a couple of days on a problem with my application running on an embedded Arm Linux platform. Unfortunately the platform precludes me from using any of the usual useful tools for finding the exact issue. When the same code is run on the PC running Linux, I get no such error. In the sample below, I can reliably reproduce the problem by uncommenting the string, list or vector lines. Leaving them commented results in the application running to completion. I expect that something is corrupting the heap, but I cannot see what? The program will run for a few seconds before giving a segmentation fault. The code is compiled using a arm-linux cross compiler: arm-linux-g++ -Wall -otest fault.cpp -ldl -lpthread arm-linux-strip test Any ideas greatly appreciated. #include <stdio.h> #include <vector> #include <list> #include <string> using namespace std; ///////////////////////////////////////////////////////////////////////////// class TestSeg { static pthread_mutex_t _logLock; public: TestSeg() { } ~TestSeg() { } static void* TestThread( void *arg ) { int i = 0; while ( i++ < 10000 ) { printf( "%d\n", i ); WriteBad( "Function" ); } pthread_exit( NULL ); } static void WriteBad( const char* sFunction ) { pthread_mutex_lock( &_logLock ); printf( "%s\n", sFunction ); //string sKiller; // <----------------------------------Bad //list<char> killer; // <----------------------------------Bad //vector<char> killer; // <----------------------------------Bad pthread_mutex_unlock( &_logLock ); return; } void RunTest() { int threads = 100; pthread_t _rx_thread[threads]; for ( int i = 0 ; i < threads ; i++ ) { pthread_create( &_rx_thread[i], NULL, TestThread, NULL ); } for ( int i = 0 ; i < threads ; i++ ) { pthread_join( _rx_thread[i], NULL ); } } }; pthread_mutex_t TestSeg::_logLock = PTHREAD_MUTEX_INITIALIZER; int main( int argc, char *argv[] ) { TestSeg seg; seg.RunTest(); pthread_exit( NULL ); }

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• JVM throws OutOfMemory during gc though there are plenty memory left...

  - by Shu L.

  I have my java application configured to use 5G memory. I got an OutOfMemory out of blue. I inspected the gc log and found plenty of memory left: young generation occupies 4% allocated space, tenure generation occupancy is 5% and perm generation is 43%. I am puzzled why JVM throws an OutOfMemory at the gc time. Does anyone know why this is happening? Your help is greatly appreciated. JVM memory and gc settings: -server -Xms5g -Xmx5g -Xss256k -XX:NewSize=2g -XX:MaxNewSize=2g -XX:+UseParallelOldGC -XX:+UseTLAB -XX:SurvivorRatio=8 -XX:TargetSurvivorRatio=90 -XX:+DisableExplicitGC gc.log 2009-09-19T03:34:59.741+0000: 92836.778: [GC Desired survivor size 152567808 bytes, new threshold 1 (max 15) [PSYoungGen: 1941492K-144057K(1947072K)] 3138022K-1340830K(5092800K), 0.1947640 secs] [Times: user=0.61 sys=0.01, real=0.19 secs] 2009-09-19T03:35:29.918+0000: 92866.954: [GC Desired survivor size 152109056 bytes, new threshold 1 (max 15) [PSYoungGen: 1941625K-144049K(1948608K)] 3138398K-1341080K(5094336K), 0.1942000 secs] [Times: user=0.61 sys=0.01, real=0.20 secs] 2009-09-19T03:35:56.883+0000: 92893.920: [GC Desired survivor size 156565504 bytes, new threshold 1 (max 15) [PSYoungGen: 1567994K-115427K(1915072K)] 2765026K-1312820K(5060800K), 0.1586320 secs] [Times: user=0.50 sys=0.01, real=0.16 secs] 2009-09-19T03:35:57.042+0000: 92894.079: [GC Desired survivor size 179961856 bytes, new threshold 1 (max 15) [PSYoungGen: 115427K-0K(1898560K)] 1312820K-1313987K(5044288K), 0.0775650 secs] [Times: user=0.42 sys=0.19, real=0.08 secs] 2009-09-19T03:35:57.120+0000: 92894.157: [Full GC [PSYoungGen: 0K-0K(1898560K)] [ParOldGen: 1313987K-159522K(3145728K)] 1313987K-159522K(5044288K) [PSPermGen: 20025K-19942K(40256K)], 0.56923 00 secs] [Times: user=2.18 sys=0.05, real=0.57 secs] 2009-09-19T03:35:57.690+0000: 92894.726: [GC Desired survivor size 197066752 bytes, new threshold 1 (max 15) [PSYoungGen: 0K-0K(1745728K)] 159522K-159522K(4891456K), 0.0072590 secs] [Times: user=0.01 sys=0.00, real=0.00 secs] 2009-09-19T03:35:57.698+0000: 92894.734: [Full GC [PSYoungGen: 0K-0K(1745728K)] [ParOldGen: 159522K-158627K(3145728K)] 159522K-158627K(4891456K) [PSPermGen: 19942K-19934K(45504K)], 0.3280480 secs] [Times: user=1.46 sys=0.00, real=0.33 secs] Heap PSYoungGen total 1745728K, used 87233K [0x00002aab73650000, 0x00002aabf3650000, 0x00002aabf3650000) eden space 1745664K, 4% used [0x00002aab73650000,0x00002aab78b80778,0x00002aabddf10000) from space 64K, 0% used [0x00002aabddf10000,0x00002aabddf10000,0x00002aabddf20000) to space 192448K, 0% used [0x00002aabe7a60000,0x00002aabe7a60000,0x00002aabf3650000) ParOldGen total 3145728K, used 158627K [0x00002aaab3650000, 0x00002aab73650000, 0x00002aab73650000) object space 3145728K, 5% used [0x00002aaab3650000,0x00002aaabd138d28,0x00002aab73650000) PSPermGen total 45504K, used 19965K [0x00002aaaae250000, 0x00002aaab0ec0000, 0x00002aaab3650000) object space 45504K, 43% used [0x00002aaaae250000,0x00002aaaaf5cf668,0x00002aaab0ec0000) I am on 64-bit Linux and JRE 1.6.0_10: $uname -a Linux x 2.6.24-etchnhalf.1-amd64 #1 SMP Tue Oct 14 03:11:45 UTC 2008 x86_64 GNU/Linux $java -version java version "1.6.0_10" Java(TM) SE Runtime Environment (build 1.6.0_10-b33) Java HotSpot(TM) 64-Bit Server VM (build 11.0-b15, mixed mode)

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• Freetype2 failing under WoW64

  - by Necrolis

  I built a tff to D3D texture function using freetype2(2.3.9) to generate grayscale maps from the fonts. it works great under native win32, however, on WoW64 it just explodes (well, FT_Done and FT_Load_Glyph do). from some debugging, it seems to be a problem with HeapFree as called by free from FT_Free. I know it should work, as games like WCIII, which to the best of my knowledge use freetype2, run fine, this is my code, stripped of the D3D code(which causes no problems on its own): FT_Face pFace = NULL; FT_Error nError = 0; FT_Byte* pFont = static_cast<FT_Byte*>(ARCHIVE_LoadFile(pBuffer,&nSize)); if((nError = FT_New_Memory_Face(pLibrary,pFont,nSize,0,&pFace)) == 0) { FT_Set_Char_Size(pFace,nSize << 6,nSize << 6,96,96); for(unsigned char c = 0; c < 95; c++) { if(!FT_Load_Glyph(pFace,FT_Get_Char_Index(pFace,c + 32),FT_LOAD_RENDER)) { FT_Glyph pGlyph; if(!FT_Get_Glyph(pFace->glyph,&pGlyph)) { LOG("GET: %c",c + 32); FT_Glyph_To_Bitmap(&pGlyph,FT_RENDER_MODE_NORMAL,0,1); FT_BitmapGlyph pGlyphMap = reinterpret_cast<FT_BitmapGlyph>(pGlyph); FT_Bitmap* pBitmap = &pGlyphMap->bitmap; const size_t nWidth = pBitmap->width; const size_t nHeight = pBitmap->rows; //add to texture atlas } } } } else { FT_Done_Face(pFace); delete pFont; return FALSE; } FT_Done_Face(pFace); delete pFont; return TRUE; } ARCHIVE_LoadFile returns blocks allocated with new. As a secondary question, I would like to render a font using pixel sizes, I came across FT_Set_Pixel_Sizes, but I'm unsure as to whether this stretches the font to fit the size, or bounds it to a size. what I would like to do is render all the glyphs at say 24px (MS Word size here), then turn it into a signed distance field in a 32px area. Update After much fiddling, I got a test app to work, which leads me to think the problems are arising from threading, as my code is running in a secondary thread. I have compiled freetype into a static lib using the multithread DLL, my app uses the multithreaded libs. gonna see if i can set up a multithreaded test. Also updated to 2.4.4, to see if the problem was a known but fixed bug, didn't help however. Update 2 After some more fiddling, it turns out I wasn't using the correct lib for 2.4.4 -.- after fixing that, the test app works 100%, but the main app still crashes when FT_Done_Face is called, still seems to be a crash in the memory heap management of windows. is it possible that there is a bug in freetype2 that makes it blow up under user threads?

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• How to optimize my PostgreSQL DB for prefix search?

  - by asmaier

  I have a table called "nodes" with roughly 1.7 million rows in my PostgreSQL db =#\d nodes Table "public.nodes" Column | Type | Modifiers --------+------------------------+----------- id | integer | not null title | character varying(256) | score | double precision | Indexes: "nodes_pkey" PRIMARY KEY, btree (id) I want to use information from that table for autocompletion of a search field, showing the user a list of the ten titles having the highest score fitting to his input. So I used this query (here searching for all titles starting with "s") =# explain analyze select title,score from nodes where title ilike 's%' order by score desc; QUERY PLAN ----------------------------------------------------------------------------------------------------------------------- Sort (cost=64177.92..64581.38 rows=161385 width=25) (actual time=4930.334..5047.321 rows=161264 loops=1) Sort Key: score Sort Method: external merge Disk: 5712kB -> Seq Scan on nodes (cost=0.00..46630.50 rows=161385 width=25) (actual time=0.611..4464.413 rows=161264 loops=1) Filter: ((title)::text ~~* 's%'::text) Total runtime: 5260.791 ms (6 rows) This was much to slow for using it with autocomplete. With some information from Using PostgreSQL in Web 2.0 Applications I was able to improve that with a special index =# create index title_idx on nodes using btree(lower(title) text_pattern_ops); =# explain analyze select title,score from nodes where lower(title) like lower('s%') order by score desc limit 10; QUERY PLAN ------------------------------------------------------------------------------------------------------------------------------------------ Limit (cost=18122.41..18122.43 rows=10 width=25) (actual time=1324.703..1324.708 rows=10 loops=1) -> Sort (cost=18122.41..18144.60 rows=8876 width=25) (actual time=1324.700..1324.702 rows=10 loops=1) Sort Key: score Sort Method: top-N heapsort Memory: 17kB -> Bitmap Heap Scan on nodes (cost=243.53..17930.60 rows=8876 width=25) (actual time=96.124..1227.203 rows=161264 loops=1) Filter: (lower((title)::text) ~~ 's%'::text) -> Bitmap Index Scan on title_idx (cost=0.00..241.31 rows=8876 width=0) (actual time=90.059..90.059 rows=161264 loops=1) Index Cond: ((lower((title)::text) ~>=~ 's'::text) AND (lower((title)::text) ~<~ 't'::text)) Total runtime: 1325.085 ms (9 rows) So this gave me a speedup of factor 4. But can this be further improved? What if I want to use '%s%' instead of 's%'? Do I have any chance of getting a decent performance with PostgreSQL in that case, too? Or should I better try a different solution (Lucene?, Sphinx?) for implementing my autocomplete feature?

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• Help me stabilize this jRun configuration (CF9/Win2k3/IIS6)

  - by jfrobishow

  Not sure if this would be better suited for ServerFault, but since I am not an admin but a developer I figured I would try SO. We've been struggling to keep our multi-server configuration stable for quite some time now. At the end of last month we were running under CF 7.0.2 on a two servers setup (one instance each). At that point we managed to get our uptime to around 1 week per instance before they would restart by themselves. Since the beginning of the month we upgraded to CF 9 and we're back to square one with multi-restart a day. Our current configuration is 2 Win2k3 servers, running a cluster of 4 instances, 2 instances per server. At this point we are pretty certain this is due to improper JVM settings. We've been toying with them and while some are more stable than others we never quite got it right. From the default: java.args=-server -Xmx512m -Dsun.io.useCanonCaches=false -XX:MaxPermSize=192m -XX:+UseParallelGC -Dcoldfusion.rootDir={application.home}/ To currently: java.args=-server -Xmx896m -Dsun.io.useCanonCaches=false -XX:MaxPermSize=512m -XX:SurvivorRatio=8 -XX:TargetSurvivorRatio=90 -XX:+UseParallelGC -Dcoldfusion.rootDir={application.home}/ -verbose:gc -Xloggc:c:/Jrun4/logs/gc/gcInstance1b.log We have determined that we do need more than the default 512MB simply by monitoring with FusionReactor, on average our amount of memory consumed is hovering in the mid 300MB and can go up to low 700MB under heavy load. Most of the crash will be logged in jrun4/bin/hs_err_pid*.log always an "Out of swap space" I've attached links to the hs_err and garbage collector log file from yesterday at the bottom of the post. The relevant part is (I think) this: Heap PSYoungGen total 89856K, used 19025K [0x55490000, 0x5b6f0000, 0x5b810000) eden space 79232K, 16% used [0x55490000,0x561a64c0,0x5a1f0000) from space 10624K, 52% used [0x5ac90000,0x5b20e2f8,0x5b6f0000) to space 10752K, 0% used [0x5a1f0000,0x5a1f0000,0x5ac70000) PSOldGen total 460416K, used 308422K [0x23810000, 0x3f9b0000, 0x55490000) object space 460416K, 66% used [0x23810000,0x36541bb8,0x3f9b0000) PSPermGen total 107520K, used 106079K [0x03810000, 0x0a110000, 0x23810000) object space 107520K, 98% used [0x03810000,0x09fa7e40,0x0a110000) From it, I gather that its the PSPermGen that is full (most logs will show the same before a crash), which is why we increased MaxPermSize but the total still show as 107520K!??! No one here is a jRun expert, so any help or even ideas on what to try next would be greatly appreciated!! The log files: Sorry I know sendspace isn't the friendliest of places - if you have other host suggestion for log files let me know and I'll update the post (SO doesn't like them inline, it blows up the format of the post). The hs_err log file: http://www.sendspace.com/file/fgak8l The gc log: http://www.sendspace.com/file/w0r2ct

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• How to I serialize a large graph of .NET object into a SQL Server BLOB without creating a large bu

  - by Ian Ringrose

  We have code like: ms = New IO.MemoryStream bin = New System.Runtime.Serialization.Formatters.Binary.BinaryFormatter bin.Serialize(ms, largeGraphOfObjects) dataToSaveToDatabase = ms.ToArray() // put dataToSaveToDatabase in a Sql server BLOB But the memory steam allocates a large buffer from the large memory heap that is giving us problems. So how can we stream the data without needing enough free memory to hold the serialized objects. I am looking for a way to get a Stream from SQL server that can then be passed to bin.Serialize() so avoiding keeping all the data in my processes memory. Likewise for reading the data back... Some more background. This is part of a complex numerical processing system that processes data in near real time looking for equipment problems etc, the serialization is done to allow a restart when there is a problem with data quality from a data feed etc. (We store the data feeds and can rerun them after the operator has edited out bad values.) Therefore we serialize the object a lot more often then we de-serialize them. The objects we are serializing include very large arrays mostly of doubles as well as a lot of small “more normal” objects. We are pushing the memory limit on a 32 bit system and make the garage collector work very hard. (Effects are being made elsewhere in the system to improve this, e.g. reusing large arrays rather then create new arrays.) Often the serialization of the state is the last straw that courses an out of memory exception; our peak memory usage is while this serialization is being done. I think we get large memory pool fragmentation when we de-serialize the object, I expect there are also other problem with large memory pool fragmentation given the size of the arrays. (This has not yet been investigated, as the person that first looked at this is a numerical processing expert, not a memory management expert.) Are customers use a mix of Sql Server 2000, 2005 and 2008 and we would rather not have different code paths for each version of Sql Server if possible. We can have many active models at a time (in different process, across many machines), each model can have many saved states. Hence the saved state is stored in a database blob rather then a file. As the spread of saving the state is important, I would rather not serialize the object to a file, and then put the file in a BLOB one block at a time. Other related questions I have asked How to Stream data from/to SQL Server BLOB fields? Is there a SqlFileStream like class that works with Sql Server 2005?

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• Java map / nio / NFS issue causing a VM fault: "a fault occurred in a recent unsafe memory access op

  - by Matthew Bloch

  I have written a parser class for a particular binary format (nfdump if anyone is interested) which uses java.nio's MappedByteBuffer to read through files of a few GB each. The binary format is just a series of headers and mostly fixed-size binary records, which are fed out to the called by calling nextRecord(), which pushes on the state machine, returning null when it's done. It performs well. It works on a development machine. On my production host, it can run for a few minutes or hours, but always seems to throw "java.lang.InternalError: a fault occurred in a recent unsafe memory access operation in compiled Java code", fingering one of the Map.getInt, getShort methods, i.e. a read operation in the map. The uncontroversial (?) code that sets up the map is this: /** Set up the map from the given filename and position */ protected void open() throws IOException { // Set up buffer, is this all the flexibility we'll need? channel = new FileInputStream(file).getChannel(); MappedByteBuffer map1 = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size()); map1.load(); // we want the whole thing, plus seems to reduce frequency of crashes? map = map1; // assumes the host writing the files is little-endian (x86), ought to be configurable map.order(java.nio.ByteOrder.LITTLE_ENDIAN); map.position(position); } and then I use the various map.get* methods to read shorts, ints, longs and other sequences of bytes, before hitting the end of the file and closing the map. I've never seen the exception thrown on my development host. But the significant point of difference between my production host and development is that on the former, I am reading sequences of these files over NFS (probably 6-8TB eventually, still growing). On my dev machine, I have a smaller selection of these files locally (60GB), but when it blows up on the production host it's usually well before it gets to 60GB of data. Both machines are running java 1.6.0_20-b02, though the production host is running Debian/lenny, the dev host is Ubuntu/karmic. I'm not convinced that will make any difference. Both machines have 16GB RAM, and are running with the same java heap settings. I take the view that if there is a bug in my code, there is enough of a bug in the JVM not to throw me a proper exception! But I think it is just a particular JVM implementation bug due to interactions between NFS and mmap, possibly a recurrence of 6244515 which is officially fixed. I already tried adding in a "load" call to force the MappedByteBuffer to load its contents into RAM - this seemed to delay the error in the one test run I've done, but not prevent it. Or it could be coincidence that was the longest it had gone before crashing! If you've read this far and have done this kind of thing with java.nio before, what would your instinct be? Right now mine is to rewrite it without nio :)

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• Understanding CLR 2.0 Memory Model

  - by Eloff

  Joe Duffy, gives 6 rules that describe the CLR 2.0+ memory model (it's actual implementation, not any ECMA standard) I'm writing down my attempt at figuring this out, mostly as a way of rubber ducking, but if I make a mistake in my logic, at least someone here will be able to catch it before it causes me grief. Rule 1: Data dependence among loads and stores is never violated. Rule 2: All stores have release semantics, i.e. no load or store may move after one. Rule 3: All volatile loads are acquire, i.e. no load or store may move before one. Rule 4: No loads and stores may ever cross a full-barrier (e.g. Thread.MemoryBarrier, lock acquire, Interlocked.Exchange, Interlocked.CompareExchange, etc.). Rule 5: Loads and stores to the heap may never be introduced. Rule 6: Loads and stores may only be deleted when coalescing adjacent loads and stores from/to the same location. I'm attempting to understand these rules. x = y y = 0 // Cannot move before the previous line according to Rule 1. x = y z = 0 // equates to this sequence of loads and stores before possible re-ordering load y store x load 0 store z Looking at this, it appears that the load 0 can be moved up to before load y, but the stores may not be re-ordered at all. Therefore, if a thread sees z == 0, then it also will see x == y. If y was volatile, then load 0 could not move before load y, otherwise it may. Volatile stores don't seem to have any special properties, no stores can be re-ordered with respect to each other (which is a very strong guarantee!) Full barriers are like a line in the sand which loads and stores can not be moved over. No idea what rule 5 means. I guess rule 6 means if you do: x = y x = z Then it is possible for the CLR to delete both the load to y and the first store to x. x = y z = y // equates to this sequence of loads and stores before possible re-ordering load y store x load y store z // could be re-ordered like this load y load y store x store z // rule 6 applied means this is possible? load y store x // but don't pop y from stack (or first duplicate item on top of stack) store z What if y was volatile? I don't see anything in the rules that prohibits the above optimization from being carried out. This does not violate double-checked locking, because the lock() between the two identical conditions prevents the loads from being moved into adjacent positions, and according to rule 6, that's the only time they can be eliminated. So I think I understand all but rule 5, here. Anyone want to enlighten me (or correct me or add something to any of the above?)

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• Android problem: BufferedReader wont read whole stream into a string

  - by Levara

  Hi all! I'm making an android program that retrieves content of a webpage using HttpURLConnection. I'm new to both Java and Android. Problem is: Reader reads whole page source, but in the last while iteration it doesn't append to stringBuffer that last part. Using debbuger I have determined that, in the last loop iteration, string buff is created, but stringBuffer just doesnt append it. I need to parse retrieved content. Is there any better way to handle the content for parsing than using strings. I've read on numerous other sites that string size in Java is limited only by available heap size. Anyone know what could be the problem. Btw feel free to suggest any improvements to the code. Thanks! URL u; try { u = new URL("http://feeds.timesonline.co.uk/c/32313/f/440134/index.rss"); HttpURLConnection c = (HttpURLConnection) u.openConnection(); c.setRequestProperty("User-agent","Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; InfoPath.1; .NET CLR 2.0.50727)"); c.setRequestMethod("GET"); c.setDoOutput(true); c.setReadTimeout(3000); c.connect(); StringBuffer stringBuffer = new StringBuffer(""); InputStream in = c.getInputStream(); InputStreamReader inp = new InputStreamReader(in); BufferedReader reader = new BufferedReader(inp); char[] buffer = new char[3072]; int len1 = 0; while ( (len1 = reader.read(buffer)) != -1 ) { String buff = new String(buffer,0,len1); stringBuffer.append(buff); } String stranica = new String(stringBuffer); c.disconnect(); reader.close(); inp.close(); in.close();

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• PHP Processes reaching limit along with FastCGI timeouts

  - by Constant M

  I have a problem similar to http://stackoverflow.com/questions/1168384/how-to-troubleshoot-php-processes, but with a twist. We have a couple of managed servers that recently migrated to FastCGI. Since then we've been having problems. We have a content management system at a central place that we manage all our sites with. All the sites run on the same managed server. So basically its one PHP script that generates pages on the same server. The catch comes in where it works perfectly on some, and gives FCGI timeout errors on others. At the same time our support is saying that the PHP processes heap up to their limit and then causes Apache to stop working. I'm convinced this is a fault on their side, but would like to get my side clean too. Anyway have any suggestions where I can start looking for what's going wrong? I know it's a really broad question, but any help or pointers would be great. Thanks Just to add to that, here's a PS printout from support: happyh 13853 21556 0 01:04 ? 00:00:00 /usr/bin/php5-cgi happyh 13869 13853 0 01:04 ? 00:00:00 /usr/bin/php5-cgi mamedc 13914 21556 0 05:14 ? 00:00:00 /usr/bin/php5-cgi wealthf 13947 21556 0 01:21 ? 00:00:00 /usr/bin/php5-cgi wealthf 13961 13947 0 01:21 ? 00:00:00 /usr/bin/php5-cgi mamedc 14032 13914 0 05:14 ? 00:00:00 /usr/bin/php5-cgi lookgrt 14157 21556 0 04:47 ? 00:00:00 /usr/bin/php5-cgi lookgrt 14178 14157 0 04:47 ? 00:00:00 /usr/bin/php5-cgi wolfie 14262 21556 0 01:08 ? 00:00:00 /usr/bin/php5-cgi wolfie 14276 14262 0 01:08 ? 00:00:00 /usr/bin/php5-cgi yaukrl 14352 21556 0 01:21 ? 00:00:00 /usr/bin/php5-cgi yaukrl 14361 14352 0 01:21 ? 00:00:00 /usr/bin/php5-cgi itpays2 14538 21556 0 01:33 ? 00:00:00 /usr/bin/php5-cgi itpays2 14547 14538 0 01:33 ? 00:00:00 /usr/bin/php5-cgi brichmbx 14732 21556 0 04:47 ? 00:00:00 /usr/bin/php5-cgi brichmbx 14803 14732 0 04:47 ? 00:00:00 /usr/bin/php5-cgi greatl 14969 21556 0 01:00 ? 00:00:00 /usr/bin/php5-cgi

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• C++ Program Always Crashes While doing a std::string assign

  - by bbazso

  I have been trying to debug a crash in my application that crashes (i.e. asserts a * glibc detected free(): invalid pointer: 0x000000000070f0c0 **) while I'm trying to do a simple assign to a string. Note that I'm compiling on a linux system with gcc 4.2.4 with an optimization level set to -O2. With -O0 the application no longer crashes. E.g. std::string abc; abc = "testString"; but if I changed the code as follows it no longer crashes std::string abc("testString"); So again I scratched my head! But the interesting pattern was that the crash moved later on in the application, AGAIN at another string. I found it weird that the application was continuously crashing on a string assign. A typical crash backtrace would look as follows: #0 0x00007f2c2663bfb5 in raise () from /lib64/libc.so.6 (gdb) bt #0 0x00007f2c2663bfb5 in raise () from /lib64/libc.so.6 #1 0x00007f2c2663dbc3 in abort () from /lib64/libc.so.6 #2 0x00000000004d8cb7 in people_streamingserver_sighandler (signum=6) at src/peoplestreamingserver.cpp:487 #3 <signal handler called> #4 0x00007f2c2663bfb5 in raise () from /lib64/libc.so.6 #5 0x00007f2c2663dbc3 in abort () from /lib64/libc.so.6 #6 0x00007f2c26680ce0 in ?? () from /lib64/libc.so.6 #7 0x00007f2c270ca7a0 in std::string::assign (this=0x7f2c21bc8d20, __str=<value optimized out>) at /home/bbazso/ThirdParty/sources/gcc-4.2.4/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.h:238 #8 0x00007f2c21bd874a in PEOPLESProtocol::GetStreamName (this=<value optimized out>, pRawPath=0x2342fd8 "rtmp://127.0.0.1/mp4:pop.mp4", lStreamName=@0x7f2c21bc8d20) at /opt/trx-HEAD/gcc/4.2.4/lib/gcc/x86_64-pc-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/basic_string.h:491 #9 0x00007f2c21bd9daa in PEOPLESProtocol::SignalProtocolCreated (pProtocol=0x233a4e0, customParameters=@0x7f2c21bc8de0) at peoplestreamer/src/peoplesprotocol.cpp:240 This was really weird behavior and so I started to poke around further in my application to see if there was some sort of memory corruption (either heap or stack) error that could be occurring that could be causing this weird behavior. I even checked for ptr corruptions and came up empty handed. In addition to visual inspection of the code I also tried the following tools: Valgrind using both memcheck and exp-ptrcheck electric fence libsafe I compiled with -fstack-protector-all in gcc I tried MALLOC_CHECK_ set to 2 I ran my code through lint checks as well as cppcheck (to check for mistakes) And I stepped through the code using gdb So I tried a lot of stuff and still came up empty handed. So I was wondering if it could be something like a linker issue or a library issue of some sort that could be causing this problem. Are there any know issues with the std::string that make is susceptible to crashing in -O2 or maybe it has nothing to do with the optimization level? But the only pattern that I can see thus far in my problem is that it always seems to crash on a string and so I was wondering if anyone knew of any issues that my be causing this type of behavior. Thanks a lot!

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• Autocomplete server-side implementation

  - by toluju

  What is a fast and efficient way to implement the server-side component for an autocomplete feature in an html input box? I am writing a service to autocomplete user queries in our web interface's main search box, and the completions are displayed in an ajax-powered dropdown. The data we are running queries against is simply a large table of concepts our system knows about, which matches roughly with the set of wikipedia page titles. For this service obviously speed is of utmost importance, as responsiveness of the web page is important to the user experience. The current implementation simply loads all concepts into memory in a sorted set, and performs a simple log(n) lookup on a user keystroke. The tailset is then used to provide additional matches beyond the closest match. The problem with this solution is that it does not scale. It currently is running up against the VM heap space limit (I've set -Xmx2g, which is about the most we can push on our 32 bit machines), and this prevents us from expanding our concept table or adding more functionality. Switching to 64-bit VMs on machines with more memory isn't an immediate option. I've been hesitant to start working on a disk-based solution as I am concerned that disk seek time will kill performance. Are there possible solutions that will let me scale better, either entirely in memory or with some fast disk-backed implementations? Edits: @Gandalf: For our use case it is important the the autocompletion is comprehensive and isn't just extra help for the user. As for what we are completing, it is a list of concept-type pairs. For example, possible entries are [("Microsoft", "Software Company"), ("Jeff Atwood", "Programmer"), ("StackOverflow.com", "Website")]. We are using Lucene for the full search once a user selects an item from the autocomplete list, but I am not yet sure Lucene would work well for the autocomplete itself. @Glen: No databases are being used here. When I'm talking about a table I just mean the structured representation of my data. @Jason Day: My original implementation to this problem was to use a Trie, but the memory bloat with that was actually worse than the sorted set due to needing a large number of object references. I'll read on the ternary search trees to see if it could be of use.

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• How to optimize this SQL query for a rectangular region?

  - by Andrew B.

  I'm trying to optimize the following query, but it's not clear to me what index or indexes would be best. I'm storing tiles in a two-dimensional plane and querying for rectangular regions of that plane. The table has, for the purposes of this question, the following columns: id: a primary key integer world_id: an integer foreign key which acts as a namespace for a subset of tiles tileY: the Y-coordinate integer tileX: the X-coordinate integer value: the contents of this tile, a varchar if it matters. I have the following indexes: "ywot_tile_pkey" PRIMARY KEY, btree (id) "ywot_tile_world_id_key" UNIQUE, btree (world_id, "tileY", "tileX") "ywot_tile_world_id" btree (world_id) And this is the query I'm trying to optimize: ywot=> EXPLAIN ANALYZE SELECT * FROM "ywot_tile" WHERE ("world_id" = 27685 AND "tileY" <= 6 AND "tileX" <= 9 AND "tileX" >= -2 AND "tileY" >= -1 ); QUERY PLAN ------------------------------------------------------------------------------------------------------------------------------------------- Bitmap Heap Scan on ywot_tile (cost=11384.13..149421.27 rows=65989 width=168) (actual time=79.646..80.075 rows=96 loops=1) Recheck Cond: ((world_id = 27685) AND ("tileY" <= 6) AND ("tileY" >= (-1)) AND ("tileX" <= 9) AND ("tileX" >= (-2))) -> Bitmap Index Scan on ywot_tile_world_id_key (cost=0.00..11367.63 rows=65989 width=0) (actual time=79.615..79.615 rows=125 loops=1) Index Cond: ((world_id = 27685) AND ("tileY" <= 6) AND ("tileY" >= (-1)) AND ("tileX" <= 9) AND ("tileX" >= (-2))) Total runtime: 80.194 ms So the world is fixed, and we are querying for a rectangular region of tiles. Some more information that might be relevant: All the tiles for a queried region may or may not be present The height and width of a queried rectangle are typically about 10x10-20x20 For any given (world, X) or (world, Y) pair, there may be an unbounded number of matching tiles, but the worst case is currently around 10,000, and typically there are far fewer. New tiles are created far less frequently than existing ones are updated (changing the 'value'), and that itself is far less frequent that just reading as in the query above. The only thing I can think of would be to index on (world, X) and (world, Y). My guess is that the database would be able to take those two sets and intersect them. The problem is that there is a potentially unbounded number of matches for either for either of those. Is there some other kind of index that would be more appropriate?

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• How can I pass managed objects from one AppDomain to another?

  - by Dennis P

  I have two assemblies that I'm trying to link together. One is a sort of background process that's built with WinForms and will be designed to run as a Windows Service. I have a second project that will act as a UI for the background process whenever a user launches it. I've never tried attempting something like this with managed code before, so I've started trying to use windows messages to communicate between the two processes. I'm struggling when it comes to passing more than just IntPtrs back and forth, however. Here's the code from a control in my UI project that registers itself with the background process: public void Init() { IntPtr hwnd = IntPtr.Zero; Process[] ps = Process.GetProcessesByName("BGServiceApp"); Process mainProcess = null; if(ps == null || ps.GetLength(0) == 0) { mainProcess = LaunchApp(); } else { mainProcess = ps[0]; } SendMessage(mainProcess.MainWindowHandle, INIT_CONNECTION, this.Handle, IntPtr.Zero); } protected override void WndProc(ref Message m) { if(m.Msg == INIT_CONFIRMED && InitComplete != null) { string message = Marshal.PtrToStringAuto(m.WParam); Marshal.FreeHGlobal(m.WParam); InitComplete(message, EventArgs.Empty); } base.WndProc(ref m); } This is the code from the background process that's supposed to receive a request from the UI process to register for status updates and send a confirmation message. protected override void WndProc(ref Message m) { if(m.Msg == INIT_CONNECTION) { RegisterUIDispatcher(m.WParam); Respond(m.WParam); } if(m.Msg == UNINIT_CONNECTION) { UnregisterUIDispatcher(m.WParam); if(m_RegisteredDispatchers.Count == 0) { this.Close(); } } base.WndProc(ref m); } private void Respond(IntPtr caller) { string test = "Registration confirmed!"; IntPtr ptr = Marshal.StringToHGlobalAuto(test); SendMessage(caller, INIT_CONFIRMED, ptr, IntPtr.Zero); } } The UI process receives the INIT_CONFIRMED message from my background process, but when I try to marshal the IntPtr back into a string, I get an empty string. Is the area of heap I'm using out of scope to the other process or am I missing some security attribute maybe? Is there a better and cleaner way to go about something like this using an event driven model?

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