Search Results

Search found 16324 results on 653 pages for 'per thread'.

Page 107/653 | < Previous Page | 103 104 105 106 107 108 109 110 111 112 113 114  | Next Page >

• Red Samurai Performance Audit Tool – OOW 2013 release (v 1.1)

  - by JuergenKress

  We are running our Red Samurai Performance Audit tool and monitoring ADF performance in various projects already for about one year and the half. It helps us a lot to understand ADF performance bottlenecks and tune slow ADF BC View Objects or optimise large ADF BC fetches from DB. There is special update implemented for OOW'13 - advanced ADF BC statistics are collected directly from your application ADF BC runtime and later displayed as graphical information in the dashboard. I will be attending OOW'13 in San Francisco, feel free to stop me and ask about this tool - I will be happy to give it away and explain how to use it in your project. Original audit screen with ADF BC performance issues, this is part of our Audit console application: Audit console v1.1 is improved with one more tab - Statistics. This tab displays all SQL Selects statements produced by ADF BC over time, logged users, AM access load distribution and number of AM activations along with user sessions. Available graphs: Daily Queries  - total number of SQL selects per day Hourly Queries - Last 48 Hours Logged Users - total number of user sessions per day SQL Selects per Application Module - workload per Application Module Number of Activations and User sessions - last 48 hours - displays stress load Read the complete article here. WebLogic Partner Community For regular information become a member in the WebLogic Partner Community please visit: http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Wiki Technorati Tags: Red Samurai,ADF performance,WebLogic,WebLogic Community,Oracle,OPN,Jürgen Kress

  Read the article

• Maintaining a main project line with satellite projects

  - by NickLarsen

  Some projects I work on have a main line of features, but are customizable per customer. Up until now those customizations have been implemented as preferences, but now there are 2 problems with the system... The settings page is getting out of control with features. There are probably some improvements that could be made to the settings UI, but regardless, it is quite cumbersome setting up new instances for new customers. Customers have started asking for customizations which would be more easily maintained as separate threads instead of having tons of customizations code. Optimally I am envisioning some kind of source control in which features are either in the main project line and customizations per customer are maintained in a repo per customer set up. The customizations per project would need to remain separate but if a bug is found and fixed in a particular project, I would need to percolate the fix back to the main line and into all of the other customer repos. The problem is I have never seen this done before, and before spending time trying to find source control that can accommodate this scenario and implement it, I figure it best to ask if anyone has something less complicated or knows of a source control product which can handle this with very little hair pulling.

  Read the article

• Frame Independent Movement

  - by ShrimpCrackers

  I've read two other threads here on movement: Time based movement Vs Frame rate based movement?, and Fixed time step vs Variable time step but I think I'm lacking a basic understanding of frame independent movement because I don't understand what either of those threads are talking about. I'm following along with lazyfoo's SDL tutorials and came upon the frame independent lesson. http://lazyfoo.net/SDL_tutorials/lesson32/index.php I'm not sure what the movement part of the code is trying to say but I think it's this (please correct me if I'm wrong): In order to have frame independent movement, we need to find out how far an object (ex. sprite) moves within a certain time frame, for example 1 second. If the dot moves at 200 pixels per second, then I need to calculate how much it moves within that second by multiplying 200 pps by 1/1000 of a second. Is that right? The lesson says: "velocity in pixels per second * time since last frame in seconds. So if the program runs at 200 frames per second: 200 pps * 1/200 seconds = 1 pixel" But...I thought we were multiplying 200 pps by 1/1000th of a second. What is this business with frames per second? I'd appreciate if someone could give me a little bit more detailed explanation as to how frame independent movement works. Thank you.

  Read the article

• Ubuntu 64bit Black Screen on Minecraft

  - by Signify

  I have tried posting on the forums, but I really need help (I'm a server admin and really don't want to have to switch to Windows just to run Minecraft). Anyhow, I originally was running openjdk6 as I was told that 7 was unstable and was getting periodical lag spikes while walking (at least once every 3 seconds the screen would freeze for a tenth of a second). After that, I attempted to install Sun's Java JDK7 (I couldn't get ahold of 6 without signing up for Oracle's newsletters). Upon attempting to run Minecraft, I got a black screen after logging in with this error message: 27 achievements 182 recipes Setting user: Thunder7102, -1618112820878091307 Exception in thread "Minecraft main thread" java.lang.UnsatisfiedLinkError: /home/noiro/.minecraft/bin/natives/liblwjgl.so: /home/noiro/.minecraft/bin/natives/liblwjgl.so: wrong ELF class: ELFCLASS32 (Possible cause: architecture word width mismatch) at java.lang.ClassLoader$NativeLibrary.load(Native Method) at java.lang.ClassLoader.loadLibrary1(ClassLoader.java:1939) at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1864) at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1825) at java.lang.Runtime.load0(Runtime.java:792) at java.lang.System.load(System.java:1059) at org.lwjgl.Sys$1.run(Sys.java:69) at java.security.AccessController.doPrivileged(Native Method) at org.lwjgl.Sys.doLoadLibrary(Sys.java:65) at org.lwjgl.Sys.loadLibrary(Sys.java:81) at org.lwjgl.Sys.<clinit>(Sys.java:98) at org.lwjgl.opengl.Display.<clinit>(Display.java:132) at net.minecraft.client.Minecraft.a(SourceFile:184) at net.minecraft.client.Minecraft.run(SourceFile:657) at java.lang.Thread.run(Thread.java:722) Now, this got me fed up, so I tried to install a Windows 7 virtual machine through virtualbox, I gave it 256mb of graphics memory with 2D and 3D acceleration and 3GB of RAM. I installed Java JDK7 for Windows (which does work from experience on my other Windows 7 partition). Once again, a black screen after login. What the heck is going on guys? My System Specs: Ubuntu 12.04 64bit Fully Updated running Gnome3 Nvidia GTS 450 1.3GB OC'd AMD Athlon II 4x 2.8Ghz 6GB of RAM So, what do you think?

  Read the article

• How exactly to implement multiple threads in a game

  - by xerwin

  So I recently started learning Java, and having a interest in playing games as well as developing them, naturally I want to create game in Java. I have experience with games in C# and C++ but all of them were single-threaded simple games. But now, I learned how easy it is to make threads in Java, I want to take things to the next level. I started thinking about how would I actually implement threading in a game. I read couple of articles that say the same thing "Usually you have thread for rendering, for updating game logic, for AI, ..." but I haven't (or didn't look hard enough) found example of implementation. My idea how to make implementation is something like this (example for AI) public class AIThread implements Runnable{ private List<AI> ai; private Player player; /*...*/ public void run() { for (int i = 0; i < ai.size(); i++){ ai.get(i).update(player); } Thread.sleep(/* sleep until the next game "tick" */); } } I think this could work. If I also had a rendering and updating thread list of AI in both those threads, since I need to draw the AI and I need to calculate the logic between player and AI(But that could be moved to AIThread, but as an example) . Coming from C++ I'm used to do thing elegantly and efficiently, and this seems like neither of those. So what would be the correct way to handle this? Should I just keep multiple copies of resources in each thread or should I have the resources on one spot, declared with synchronized keyword? I'm afraid that could cause deadlocks, but I'm not yet qualified enough to know when a code will produce deadlock.

  Read the article

• New SPC2 benchmark- The 7420 KILLS it !!!

  - by user12620172

  This is pretty sweet. The new SPC2 benchmark came out last week, and the 7420 not only came in 2nd of ALL speed scores, but came in #1 for price per MBPS. Check out this table. The 7420 score of 10,704 makes it really fast, but that's not the best part. The price one would have to pay in order to beat it is ridiculous. You can go see for yourself at http://www.storageperformance.org/results/benchmark_results_spc2The only system on the whole page that beats it was over twice the price per MBPS. Very sweet for Oracle. So let's see, the 7420 is the fastest per $. The 7420 is the cheapest per MBPS. The 7420 has incredible, built-in features, management services, analytics, and protocols. It's extremely stable and as a cluster has no single point of failure. It won the Storage Magazine award for best NAS system this year. So how long will it be before it's the number 1 NAS system in the market? What are the biggest hurdles still stopping the widespread adoption of the ZFSSA? From what I see, it's three things: 1. Administrator's comfort level with older legacy systems. 2. Politics 3. Past issues with Oracle Support.   I see all of these issues crop up regularly. Number 1 just takes time and education. Number 3 takes time with our new, better, and growing support team. many of them came from Oracle and there were growing pains when they went from a straight software-model to having to also support hardware. Number 2 is tricky, but it's the job of the sales teams to break through the internal politics and help their clients see the value in oracle hardware systems. Benchmarks like this will help.

  Read the article

• Working as a contractor--questions part II

  - by universe_hacker

  This is a follow-up to this discussion: Working as a contractor--questions I still would like to get more info on the following points, when working as a contractor as opposed to direct employee: Housing: for short-term contracts (let's say 6 months or less) that are not in your home area, where and how do you search for short-term, flexible housing? Especially since an employer would typically want you to start immediately, so you don't have the time to go out and explore. Also, would you typically look for furnished apartments because the cost transporting your own furniture for a few months is not justified? Work hours and pay: are contractors more strictly supervised (as far as getting specified work done) because they get paid by the hour? There are also supposed to get overtime pay (at a higher rate) if they work more than 40 hours per week, does this really happen? Or do they work unpaid extra hours just like many regular employees? Some potential employers have mentioned paying the "per diem", which is essentially a non-taxable daily allowance, which is supposed to be used for living expenses. This money gets subtracted from you per-hour rate, but the advantage is that you pay less tax. However, from the information I have seen, the per diem can only be paid if you maintain a "permanent" residence you intend to return to. Is this checked in practice, and if yes, how?

  Read the article

• How to handle multiple pages of the same site with the same outlinks

  - by pandafromchina

  I am developing a back link tool for Chinese SEO (our web site URL is: http://link.aizhan.com just like ahrefs.com. I encountered a problem which is how to handle multiple pages of the same site with the same out links. For example: Most pages of bbs.chinaz.com have the same out links such as: bbs.chinaz.com/Tea/thread-6293993-1-1.html bbs.chinaz.com/Tea/list-1.html bbs.chinaz.com/alimama/thread-6265032-1-1.html bbs.chinaz.com/alimama/thread-6265032-2-1.html?userid=-1&extParms= bbs.chinaz.com/Shuiba/list-1.html bbs.chinaz.com/FeedBack/thread-4456753-1-1.html etc.. All of the pages have the same out links in the top of the page: www.cnzz.com(anchor text:????) www.313.com(????) www.idc123.com(????) Suppose I store these outlinks into database. The SEO will find there are six backlinks from bbs.chinaz.com of www.cnzz.com. This is obviously no sense for the SEO. Can you tell me how do you deal with this problem?

  Read the article

• Single CAS web application in a cluster

  - by Dolf Dijkstra

  Recently a customer wanted to set up a cluster of CAS nodes to be used together with WebCenter Sites. In the process of setting this up they realized that they needed to create a web application per managed server. They did not want to have this management burden but would like to have one web application deployed to multiple nodes. The reason that there is a need for a unique application per node is that the web-application contains information that needs to be unique per node, the postfix for the ticket id.  My customer would like to externalize the node specific configuration to either a specific classpath per managed server or to system properties set at startup.It turns out that the postfix for ticket ids is managed through a property host.name and that this property can be externalized.The host.name property is used in: /webapps/cas/WEB-INF/spring-configuration/uniqueIdGenerators.xmlIt is set in /webapps/cas/WEB-INF/spring-configuration/propertyFileConfigurer.xmlin a PropertyPlaceholderConfigurer.The documentation for PropertyPlaceholderConfigurer:http://static.springsource.org/spring/docs/2.0.x/api/org/springframework/beans/factory/config/PropertyPlaceholderConfigurer.htmlThis indicates that the properties defined through the PropertyPlaceHolderConfigurer can be externalized.To enable this externalization you would need to change host.properties so it is generic for all the managed servers and thus can be reused for all the managed servers: host.name=${cluster.node.id}Next step is to change the startup scripts for the managed servers and add a system property for -Dcluster.node.id=<something unique and stable>.Viola, the postfix is externalized and the web application can be shared amongst the cluster nodes.

  Read the article

• Marking Discussions as Answered

  As a contributor to a number of projects on CodePlex I really like the fact that the discussions feature exists but also I need ways to help me sort the discussions threads so I can make sure no-one is getting forgotten about. Seems like a lot of you agreed as the feature request Provide feature to allow Coordinators to mark Discussions threads as 'Answered' is our number 2 voted feature right now with 178 votes.  Today we rolled out the first iteration of “answer” support to discussions. In this first iteration we wanted to keep it simple and lightweight. The original poster of the thread along with project owners, developers or editors can mark any post to the thread as an answer. You can have any number of answers marked in a thread and it’s very quick to mark or unmark a post as an answer.  We deliberately keep the answers in the originally posted order so that you can see them in context with the discussion thread. When viewing discussions the default view is still to see everything, but you can easily filter by “Unanswered”.  You can even save that as a bookmark so as someone interested in the project can quickly jump to the unanswered discussion threads to go help out on. As I mention, we kept this first pass of the answering feature as simple and as lightweight as possible so that we can get some feedback on it. Head on over to the issue tracking this feature if you have any thoughts once you have used it for a bit or feel free to respond in the comments. I already have a couple of things I think we want to do such as a refresh of the look and feel of discussions in general along, make it easier to navigate to posts that are marked an answered and surface posts that you do that were marked as answered in your profile page - but if you have ideas then please let us know.

  Read the article

• How to dynamically override a method in an object

  - by Ace Takwas

  If this is possible, how can I change what a method does after I might have created an instance of that class and wish to keep the reference to that object but override a public method in it's class' definition? Here's my code: package time_applet; public class TimerGroup implements Runnable{ private Timer hour, min, sec; private Thread hourThread, minThread, secThread; public TimerGroup(){ hour = new HourTimer(); min = new MinuteTimer(); sec = new SecondTimer(); } public void run(){ hourThread.start(); minThread.start(); secThread.start(); } /*Please pay close attention to this method*/ private Timer activateHourTimer(int start_time){ hour = new HourTimer(start_time){ public void run(){ while (true){ if(min.changed)//min.getTime() == 0) changeTime(); } } }; hourThread = new Thread(hour); return hour; } private Timer activateMinuteTimer(int start_time){ min = new MinuteTimer(start_time){ public void run(){ while (true){ if(sec.changed)//sec.getTime() == 0) changeTime(); } } }; minThread = new Thread(min); return min; } private Timer activateSecondTimer(int start_time){ sec = new SecondTimer(start_time); secThread = new Thread(sec); return sec; } public Timer addTimer(Timer timer){ if (timer instanceof HourTimer){ hour = timer; return activateHourTimer(timer.getTime()); } else if (timer instanceof MinuteTimer){ min = timer; return activateMinuteTimer(timer.getTime()); } else{ sec = timer; return activateSecondTimer(timer.getTime()); } } } So for example in the method activateHourTimer(), I would like to override the run() method of the hour object without having to create a new object. How do I go about that?

  Read the article

• ??????????/??????????????|WebLogic Channel|??????

  - by ???02

  WebLogic Server???????????????????????????????????????????????????????????????????????????1???????????????????????????????????????????????????WebLogic Server???????????????????????????????????????????????????????????????????????·?????????????????????·??????????????????????????????????????????????????2011?11????????Oracle DBA & Developers Days 2011??????????????????????????WebLogic Server??????????????????WebLogic Server???????????????????????????????????????????????????·?????????????????????????????2??????????????????????????????????????????????·??????????(???)?WebLogic Server??????????????????????　WebLogic Server????????????????????????????OS???JVM???WebLogic Server????????????????5????????????????WebLogic Server??????????????????????????????????????　????????·????????????????????WebLogic Server????????????????　?????????????????????????????????????Listen????????????????Listen????????Muxer??????????????·????·????????????????????????????????????????·????????????????·?????????????????????????????????????????????????????????????????????????????????JDBC?????????????????????????????????????¦???????????·??????????――?????·??????·???????????WebLogic?????　?????????????????????·?????????????????????????3????????????1????????·?????????????¦????????????! ?????????????????JRockit Flight Recorder?????????1??????????????――?????????????????　1??????????????????　???????????????????????????????????????????????????????·?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????　??????????????????????CPU??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????　??????????????????????????????????????????????????????????????????????????????????????¦????????????WebLogic Server - ???????·??????　????????????????????????WebLogic Server?????????????????????????????????????????????????????????????3???　??????????????????????????(????????)??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????　??3??????????????????????????????????????????????????????????????????????　????????????50~600???????????????100~500???????????????????????????????????????????????300??????????????????????200?400???????????????????????????　???50?100???????????????????????????????????????????????????????????????????????????????????????????500?600????????????????????????????????????????????????????????????????　??????????????????????????????50?100????????????500?600???????????????????100~500?????????????????????????????????????????200~400?????????????????????????????　???????????????????????????????????????????????????????????????????"????????"??????????????????????????JDBC?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????¦????WebLogic Server(JRockit) - ????????????????????????????????2???????????????――???????? ? ??????????????????　2???????????????????????????????????????????????????????????????????????????????????????????????????????????1???????????400??????(???????????????????????????????domain.xsd????????????????????????????????????????)?　???????????????????????????????????????????????????????????????????????????????????????????????????????????????????Dweblogic.SelfTuningThreadPoolSizeMin={???????}Dweblogic.SelfTuningThreadPoolSizeMax={???????}?????????????????<server>　　<name>MANAGED_SRV</name>　　<self-tuning-thread-pool-size-min>{???????}</self-tuning-thread-pool-size-min>　　<self-tuning-thread-pool-size-max>{???????}</self-tuning-thread-pool-size-max>　　...?...</server>　????????????????????????????????????????????????????????　??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????¦????????????WebLogic Server - ????????/????　?????1?????????????·???????????????????????????????????????????????????·??????????????????????????????????·?????????????0~2????????????????????????????????????????????????????????????????????????????????????????·???????????????????????????????????????????????????????????????????????????????????　??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????·???????????????????????????????????　???????????????????????????????????????????????????????????????????????????????????????????????????????????·????????????　???????????????????????????????????????????????????????????????????????·???????????????????????????????　????????????????WebLogic Server??????????????????????????????????????????????????????????????????????????????????????????????????????????????·??????????????　??????????????????????????2????????·??????????????????????2?????????????¦Oracle DBA & Developers Days 2011????????????????????WebLogic Server??????????????¦????·????Oracle WebLogic Server 12c Forum - ????????Java??????????? -??2012?1?25?13:30~17:00 ?? ????????????13F?????

  Read the article

• Hung JVM consuming 100% CPU

  - by Bogdan

  We have a JAVA server running on Sun JRE 6u20 on Linux 32-bit (CentOS). We use the Server Hotspot with CMS collector with the following options (I've only provided the relevant ones): -Xmx896m -Xss128k -XX:NewSize=384M -XX:MaxPermSize=96m -XX:+UseParNewGC -XX:+UseConcMarkSweepGC Sometimes, after running for a while, the JVM seems to slip into a hung state, whereby even though we don't make any requests to the application, the CPU continues to spin at 100% (we have 8 logical CPUs, so it looks like only one CPU does the spinning). In this state the JVM doesn't respond to SIGHUP signals (kill -3) and we can't connect to it normally with jstack. We CAN connect with "jstack -F", but the output is dodgy (we can see lots of NullPointerExceptions from JStack apparently because it wasn't able to 'walk' some stacks). So the "jstack -F" output seems to be useless. We have run a stack dump from "gdb" though, and we were able to match the thread id that spins the CPU (we found that using "top" with a per-thread view - "H" option) with a thread stack that appears in the gdb result and this is how it looks like: Thread 443 (Thread 0x7e5b90 (LWP 26310)): #0 0x0115ebd3 in CompactibleFreeListSpace::block_size(HeapWord const*) const () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #1 0x01160ff9 in CompactibleFreeListSpace::prepare_for_compaction(CompactPoint*) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #2 0x0123456c in Generation::prepare_for_compaction(CompactPoint*) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #3 0x01229b2c in GenCollectedHeap::prepare_for_compaction() () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #4 0x0122a7fc in GenMarkSweep::invoke_at_safepoint(int, ReferenceProcessor*, bool) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #5 0x01186024 in CMSCollector::do_compaction_work(bool) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #6 0x011859ee in CMSCollector::acquire_control_and_collect(bool, bool) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #7 0x01185705 in ConcurrentMarkSweepGeneration::collect(bool, bool, unsigned int, bool) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #8 0x01227f53 in GenCollectedHeap::do_collection(bool, bool, unsigned int, bool, int) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #9 0x0115c7b5 in GenCollectorPolicy::satisfy_failed_allocation(unsigned int, bool) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #10 0x0122859c in GenCollectedHeap::satisfy_failed_allocation(unsigned int, bool) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #11 0x0158a8ce in VM_GenCollectForAllocation::doit() () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #12 0x015987e6 in VM_Operation::evaluate() () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #13 0x01597c93 in VMThread::evaluate_operation(VM_Operation*) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #14 0x01597f0f in VMThread::loop() () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #15 0x015979f0 in VMThread::run() () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #16 0x0145c24e in java_start(Thread*) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #17 0x00ccd46b in start_thread () from /lib/libpthread.so.0 #18 0x00bc2dbe in clone () from /lib/libc.so.6 It seems that a JVM thread is spinning while doing some CMS related work. We have checked the memory usage on the box, there seems to be enough memory available and the system is not swapping. Has anyone come across such a situation? Does it look like a JVM bug? UPDATE I've obtained some more information about this problem (it happened again on a server that has been running for more than 7 days). When the JVM entered the "hung" state it stayed like that for 2 hours until the server was manually restarted. We have obtained a core dump of the process and the gc log. We tried to get a heap dump as well, but "jmap" failed. We tried to use jmap -F but then only a 4Mb file was written before the program aborted with an exception (something about the a memory location not being accessible). So far I think the most interesting information comes from the gc log. It seems that the GC logging stopped as well (possibly at the time when the VM thread went into the long loop): 657501.199: [Full GC (System) 657501.199: [CMS: 400352K->313412K(524288K), 2.4024120 secs] 660634K->313412K(878208K), [CMS Perm : 29455K->29320K(68568K)], 2.4026470 secs] [Times: user=2.39 sys=0.01, real=2.40 secs] 657513.941: [GC 657513.941: [ParNew: 314624K->13999K(353920K), 0.0228180 secs] 628036K->327412K(878208K), 0.0230510 secs] [Times: user=0.08 sys=0.00, real=0.02 secs] 657523.772: [GC 657523.772: [ParNew: 328623K->17110K(353920K), 0.0244910 secs] 642036K->330523K(878208K), 0.0247140 secs] [Times: user=0.08 sys=0.00, real=0.02 secs] 657535.473: [GC 657535.473: [ParNew: 331734K->20282K(353920K), 0.0259480 secs] 645147K->333695K(878208K), 0.0261670 secs] [Times: user=0.11 sys=0.00, real=0.02 secs] .... .... 688346.765: [GC [1 CMS-initial-mark: 485248K(524288K)] 515694K(878208K), 0.0343730 secs] [Times: user=0.03 sys=0.00, real=0.04 secs] 688346.800: [CMS-concurrent-mark-start] 688347.964: [CMS-concurrent-mark: 1.083/1.164 secs] [Times: user=2.52 sys=0.09, real=1.16 secs] 688347.964: [CMS-concurrent-preclean-start] 688347.969: [CMS-concurrent-preclean: 0.004/0.005 secs] [Times: user=0.00 sys=0.01, real=0.01 secs] 688347.969: [CMS-concurrent-abortable-preclean-start] CMS: abort preclean due to time 688352.986: [CMS-concurrent-abortable-preclean: 2.351/5.017 secs] [Times: user=3.83 sys=0.38, real=5.01 secs] 688352.987: [GC[YG occupancy: 297806 K (353920 K)]688352.987: [Rescan (parallel) , 0.1815250 secs]688353.169: [weak refs processing, 0.0312660 secs] [1 CMS-remark: 485248K(524288K)] 783055K(878208K), 0.2131580 secs] [Times: user=1.13 sys =0.00, real=0.22 secs] 688353.201: [CMS-concurrent-sweep-start] 688353.903: [CMS-concurrent-sweep: 0.660/0.702 secs] [Times: user=0.91 sys=0.07, real=0.70 secs] 688353.903: [CMS-concurrent-reset-start] 688353.912: [CMS-concurrent-reset: 0.008/0.008 secs] [Times: user=0.01 sys=0.00, real=0.01 secs] 688354.243: [GC 688354.243: [ParNew: 344928K->30151K(353920K), 0.0305020 secs] 681955K->368044K(878208K), 0.0308880 secs] [Times: user=0.15 sys=0.00, real=0.03 secs] .... .... 688943.029: [GC 688943.029: [ParNew: 336531K->17143K(353920K), 0.0237360 secs] 813250K->494327K(878208K), 0.0241260 secs] [Times: user=0.10 sys=0.00, real=0.03 secs] 688950.620: [GC 688950.620: [ParNew: 331767K->22442K(353920K), 0.0344110 secs] 808951K->499996K(878208K), 0.0347690 secs] [Times: user=0.11 sys=0.00, real=0.04 secs] 688956.596: [GC 688956.596: [ParNew: 337064K->37809K(353920K), 0.0488170 secs] 814618K->515896K(878208K), 0.0491550 secs] [Times: user=0.18 sys=0.04, real=0.05 secs] 688961.470: [GC 688961.471: [ParNew (promotion failed): 352433K->332183K(353920K), 0.1862520 secs]688961.657: [CMS I suspect this problem has something to do with the last line in the log (I've added some "...." in order to skip some lines that were not interesting). The fact that the server stayed in the hung state for 2 hours (probably trying to GC and compact the old generation) seems quite strange to me. Also, the gc log stops suddenly with that message and nothing else gets printed any more, probably because the VM Thread gets into some sort of infinite loop (or something that takes 2+ hours).

  Read the article

• Fail to analyze core dump with GDB when main.elf is dynamically linked (uses shared libs)

  - by dscTobi

  Hi all. I'm trying to analyze core dump, but i get following result: GNU gdb 6.6.0.20070423-cvs Copyright (C) 2006 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "--host=mipsel-linux --target=mipsel-linux-uclibc". (gdb) file main.elf Reading symbols from /home/tobi/main.elf...Reading symbols from /home/tobi/main.dbg...done. done. (gdb) core-file /srv/tobi/core warning: .dynamic section for "/lib/libpthread.so.0" is not at the expected address (wrong library or version mismatch?) Error while mapping shared library sections: /lib/libdl.so.0: No such file or directory. Error while mapping shared library sections: /lib/librt.so.0: No such file or directory. Error while mapping shared library sections: /lib/libm.so.0: No such file or directory. Error while mapping shared library sections: /lib/libstdc++.so.6: No such file or directory. Error while mapping shared library sections: /lib/libc.so.0: No such file or directory. warning: .dynamic section for "/lib/libgcc_s.so.1" is not at the expected address (wrong library or version mismatch?) Error while mapping shared library sections: /lib/ld-uClibc.so.0: No such file or directory. Reading symbols from /lib/libpthread.so.0...done. Loaded symbols for /lib/libpthread.so.0 Symbol file not found for /lib/libdl.so.0 Symbol file not found for /lib/librt.so.0 Symbol file not found for /lib/libm.so.0 Symbol file not found for /lib/libstdc++.so.6 Symbol file not found for /lib/libc.so.0 Reading symbols from /lib/libgcc_s.so.1...done. Loaded symbols for /lib/libgcc_s.so.1 Symbol file not found for /lib/ld-uClibc.so.0 warning: Unable to find dynamic linker breakpoint function. GDB will be unable to debug shared library initializers and track explicitly loaded dynamic code. Core was generated by 'root/main.elf'. Program terminated with signal 11, Segmentation fault. #0 0x0046006c in NullPtr (parse_p=0x2ac9dc80, result_sym_p=0x13e3d6c "") at folder/my1.c:1624 1624 *ptr += 13; (gdb) bt #0 0x0046006c in NullPtr (parse_p=0x2ac9dc80, result_sym_p=0x13e3d6c "") at folder/my1.c:1624 #1 0x0047a31c in fn1 (line_ptr=0x2ac9dd18 "ccore_null_pointer", target_ptr=0x13e3d6c "", result_ptr=0x2ac9dd14) at folder/my2.c:980 #2 0x0047b9d0 in fn2 (macro_ptr=0x0, rtn_exp_ptr=0x0) at folder/my3.c:1483 /... some functions .../ #8 0x2aab7f9c in __nptl_setxid () from /lib/libpthread.so.0 Backtrace stopped: frame did not save the PC (gdb) thread apply all bt Thread 159 (process 1093): #0 0x2aac15dc in _Unwind_GetCFA () from /lib/libpthread.so.0 #1 0x2afdfde8 in ?? () warning: GDB cant find the start of the function at 0x2afdfde8. GDB is unable to find the start of the function at 0x2afdfde8 and thus cant determine the size of that functions stack frame. This means that GDB may be unable to access that stack frame, or the frames below it. This problem is most likely caused by an invalid program counter or stack pointer. However, if you think GDB should simply search farther back from 0x2afdfde8 for code which looks like the beginning of a function, you can increase the range of the search using the set heuristic-fence-post command. Backtrace stopped: previous frame inner to this frame (corrupt stack?) Thread 158 (process 1051): #0 0x2aac17bc in pthread_mutexattr_getprioceiling () from /lib/libpthread.so.0 #1 0x2aac17a0 in pthread_mutexattr_getprioceiling () from /lib/libpthread.so.0 Backtrace stopped: previous frame identical to this frame (corrupt stack?) Thread 157 (process 1057): #0 0x2aabf908 in ?? () from /lib/libpthread.so.0 #1 0x00000000 in ?? () Thread 156 (process 1090): #0 0x2aac17bc in pthread_mutexattr_getprioceiling () from /lib/libpthread.so.0 #1 0x2aac17a0 in pthread_mutexattr_getprioceiling () from /lib/libpthread.so.0 Backtrace stopped: previous frame identical to this frame (corrupt stack?) Thread 155 (process 1219): #0 0x2aabf908 in ?? () from /lib/libpthread.so.0 #1 0x00000000 in ?? () Thread 154 (process 1218): #0 0x2aabfb44 in connect () from /lib/libpthread.so.0 #1 0x00000000 in ?? () Thread 153 (process 1096): #0 0x2abc92b4 in ?? () warning: GDB cant find the start of the function at 0x2abc92b4. #1 0x2abc92b4 in ?? () warning: GDB cant find the start of the function at 0x2abc92b4. Backtrace stopped: previous frame identical to this frame (corrupt stack?) Thread 152 (process 1170): #0 0x2aabfb44 in connect () from /lib/libpthread.so.0 #1 0x00000000 in ?? () If i make main.elf statically linked everything is OK and i can see bt of all threads. Any ideas?

  Read the article

• InternalsVisibleTo attribute and security vulnerability

  - by Sergey Litvinov

  I found one issue with InternalsVisibleTo attribute usage. The idea of InternalsVisibleTo attribute to allow some other assemblies to use internal classes\methods of this assembly. To make it work you need sign your assemblies. So, if other assemblies isn't specified in main assembly and if they have incorrect public key, then they can't use Internal members. But the issue in Reflection Emit type generation. For example, we have CorpLibrary1 assembly and it has such class: public class TestApi { internal virtual void DoSomething() { Console.WriteLine("Base DoSomething"); } public void DoApiTest() { // some internal logic // ... // call internal method DoSomething(); } } This assembly is marked with such attribute to allow another CorpLibrary2 to make inheritor for that TestAPI and override behaviour of DoSomething method. [assembly: InternalsVisibleTo("CorpLibrary2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100434D9C5E1F9055BF7970B0C106AAA447271ECE0F8FC56F6AF3A906353F0B848A8346DC13C42A6530B4ED2E6CB8A1E56278E664E61C0D633A6F58643A7B8448CB0B15E31218FB8FE17F63906D3BF7E20B9D1A9F7B1C8CD11877C0AF079D454C21F24D5A85A8765395E5CC5252F0BE85CFEB65896EC69FCC75201E09795AAA07D0")] The issue is that I'm able to override this internal DoSomething method and break class logic. My steps to do it: Generate new assembly in runtime via AssemblyBuilder Get AssemblyName from CorpLibrary1 and copy PublikKey to new assembly Generate new assembly that will inherit TestApi class As PublicKey and name of generated assembly is the same as in InternalsVisibleTo, then we can generate new DoSomething method that will override internal method in TestAPI assembly Then we have another assembly that isn't related to this CorpLibrary1 and can't use internal members. We have such test code in it: class Program { static void Main(string[] args) { var builder = new FakeBuilder(InjectBadCode, "DoSomething", true); TestApi fakeType = builder.CreateFake(); fakeType.DoApiTest(); // it will display: // Inject bad code // Base DoSomething Console.ReadLine(); } public static void InjectBadCode() { Console.WriteLine("Inject bad code"); } } And this FakeBuilder class has such code: /// /// Builder that will generate inheritor for specified assembly and will overload specified internal virtual method /// /// Target type public class FakeBuilder { private readonly Action _callback; private readonly Type _targetType; private readonly string _targetMethodName; private readonly string _slotName; private readonly bool _callBaseMethod; public FakeBuilder(Action callback, string targetMethodName, bool callBaseMethod) { int randomId = new Random((int)DateTime.Now.Ticks).Next(); _slotName = string.Format("FakeSlot_{0}", randomId); _callback = callback; _targetType = typeof(TFakeType); _targetMethodName = targetMethodName; _callBaseMethod = callBaseMethod; } public TFakeType CreateFake() { // as CorpLibrary1 can't use code from unreferences assemblies, we need to store this Action somewhere. // And Thread is not bad place for that. It's not the best place as it won't work in multithread application, but it's just a sample LocalDataStoreSlot slot = Thread.AllocateNamedDataSlot(_slotName); Thread.SetData(slot, _callback); // then we generate new assembly with the same nameand public key as target assembly trusts by InternalsVisibleTo attribute var newTypeName = _targetType.Name + "Fake"; var targetAssembly = Assembly.GetAssembly(_targetType); AssemblyName an = new AssemblyName(); an.Name = GetFakeAssemblyName(targetAssembly); // copying public key to new generated assembly var assemblyName = targetAssembly.GetName(); an.SetPublicKey(assemblyName.GetPublicKey()); an.SetPublicKeyToken(assemblyName.GetPublicKeyToken()); AssemblyBuilder assemblyBuilder = Thread.GetDomain().DefineDynamicAssembly(an, AssemblyBuilderAccess.RunAndSave); ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule(assemblyBuilder.GetName().Name, true); // create inheritor for specified type TypeBuilder typeBuilder = moduleBuilder.DefineType(newTypeName, TypeAttributes.Public | TypeAttributes.Class, _targetType); // LambdaExpression.CompileToMethod can be used only with static methods, so we need to create another method that will call our Inject method // we can do the same via ILGenerator, but expression trees are more easy to use MethodInfo methodInfo = CreateMethodInfo(moduleBuilder); MethodBuilder methodBuilder = typeBuilder.DefineMethod(_targetMethodName, MethodAttributes.Public | MethodAttributes.Virtual); ILGenerator ilGenerator = methodBuilder.GetILGenerator(); // call our static method that will call inject method ilGenerator.EmitCall(OpCodes.Call, methodInfo, null); // in case if we need, then we put call to base method if (_callBaseMethod) { var baseMethodInfo = _targetType.GetMethod(_targetMethodName, BindingFlags.NonPublic | BindingFlags.Instance); // place this to stack ilGenerator.Emit(OpCodes.Ldarg_0); // call the base method ilGenerator.EmitCall(OpCodes.Call, baseMethodInfo, new Type[0]); // return ilGenerator.Emit(OpCodes.Ret); } // generate type, create it and return to caller Type cheatType = typeBuilder.CreateType(); object type = Activator.CreateInstance(cheatType); return (TFakeType)type; } /// /// Get name of assembly from InternalsVisibleTo AssemblyName /// private static string GetFakeAssemblyName(Assembly assembly) { var internalsVisibleAttr = assembly.GetCustomAttributes(typeof(InternalsVisibleToAttribute), true).FirstOrDefault() as InternalsVisibleToAttribute; if (internalsVisibleAttr == null) { throw new InvalidOperationException("Assembly hasn't InternalVisibleTo attribute"); } var ind = internalsVisibleAttr.AssemblyName.IndexOf(","); var name = internalsVisibleAttr.AssemblyName.Substring(0, ind); return name; } /// /// Generate such code: /// ((Action)Thread.GetData(Thread.GetNamedDataSlot(_slotName))).Invoke(); /// private LambdaExpression MakeStaticExpressionMethod() { var allocateMethod = typeof(Thread).GetMethod("GetNamedDataSlot", BindingFlags.Static | BindingFlags.Public); var getDataMethod = typeof(Thread).GetMethod("GetData", BindingFlags.Static | BindingFlags.Public); var call = Expression.Call(allocateMethod, Expression.Constant(_slotName)); var getCall = Expression.Call(getDataMethod, call); var convCall = Expression.Convert(getCall, typeof(Action)); var invokExpr = Expression.Invoke(convCall); var lambda = Expression.Lambda(invokExpr); return lambda; } /// /// Generate static class with one static function that will execute Action from Thread NamedDataSlot /// private MethodInfo CreateMethodInfo(ModuleBuilder moduleBuilder) { var methodName = "_StaticTestMethod_" + _slotName; var className = "_StaticClass_" + _slotName; TypeBuilder typeBuilder = moduleBuilder.DefineType(className, TypeAttributes.Public | TypeAttributes.Class); MethodBuilder methodBuilder = typeBuilder.DefineMethod(methodName, MethodAttributes.Static | MethodAttributes.Public); LambdaExpression expression = MakeStaticExpressionMethod(); expression.CompileToMethod(methodBuilder); var type = typeBuilder.CreateType(); return type.GetMethod(methodName, BindingFlags.Static | BindingFlags.Public); } } remarks about sample: as we need to execute code from another assembly, CorpLibrary1 hasn't access to it, so we need to store this delegate somewhere. Just for testing I stored it in Thread NamedDataSlot. It won't work in multithreaded applications, but it's just a sample. I know that we use Reflection to get private\internal members of any class, but within reflection we can't override them. But this issue is allows anyone to override internal class\method if that assembly has InternalsVisibleTo attribute. I tested it on .Net 3.5\4 and it works for both of them. How does it possible to just copy PublicKey without private key and use it in runtime? The whole sample can be found there - https://github.com/sergey-litvinov/Tests_InternalsVisibleTo UPDATE1: That test code in Program and FakeBuilder classes hasn't access to key.sn file and that library isn't signed, so it hasn't public key at all. It just copying it from CorpLibrary1 by using Reflection.Emit

  Read the article

• 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; } } }

  Read the article

• General monitoring for SQL Server Analysis Services using Performance Monitor

  - by Testas

  A recent customer engagement required a setup of a monitoring solution for SSAS, due to the time restrictions placed upon this, native Windows Performance Monitor (Perfmon) and SQL Server Profiler Monitoring Tools was used as using a third party tool would have meant the customer providing an additional monitoring server that was not available.I wanted to outline the performance monitoring counters that was used to monitor the system on which SSAS was running. Due to the slow query performance that was occurring during certain scenarios, perfmon was used to establish if any pressure was being placed on the Disk, CPU or Memory subsystem when concurrent connections access the same query, and Profiler to pinpoint how the query was being managed within SSAS, profiler I will leave for another blogThis guide is not designed to provide a definitive list of what should be used when monitoring SSAS, different situations may require the addition or removal of counters as presented by the situation. However I hope that it serves as a good basis for starting your monitoring of SSAS. I would also like to acknowledge Chris Webb’s awesome chapters from “Expert Cube Development” that also helped shape my monitoring strategy:http://cwebbbi.spaces.live.com/blog/cns!7B84B0F2C239489A!6657.entrySimulating ConnectionsTo simulate the additional connections to the SSAS server whilst monitoring, I used ascmd to simulate multiple connections to the typical and worse performing queries that were identified by the customer. A similar sript can be downloaded from codeplex at http://www.codeplex.com/SQLSrvAnalysisSrvcs.     File name: ASCMD_StressTestingScripts.zip. Performance MonitorWithin performance monitor,  a counter log was created that contained the list of counters below. The important point to note when running the counter log is that the RUN AS property within the counter log properties should be changed to an account that has rights to the SSAS instance when monitoring MSAS counters. Failure to do so means that the counter log runs under the system account, no errors or warning are given while running the counter log, and it is not until you need to view the MSAS counters that they will not be displayed if run under the default account that has no right to SSAS. If your connection simulation takes hours, this could prove quite frustrating if not done beforehand JThe counters used……  Object Counter Instance Justification System Processor Queue legnth N/A Indicates how many threads are waiting for execution against the processor. If this counter is consistently higher than around 5 when processor utilization approaches 100%, then this is a good indication that there is more work (active threads) available (ready for execution) than the machine's processors are able to handle. System Context Switches/sec N/A Measures how frequently the processor has to switch from user- to kernel-mode to handle a request from a thread running in user mode. The heavier the workload running on your machine, the higher this counter will generally be, but over long term the value of this counter should remain fairly constant. If this counter suddenly starts increasing however, it may be an indicating of a malfunctioning device, especially if the Processor\Interrupts/sec\(_Total) counter on your machine shows a similar unexplained increase Process % Processor Time sqlservr Definately should be used if Processor\% Processor Time\(_Total) is maxing at 100% to assess the effect of the SQL Server process on the processor Process % Processor Time msmdsrv Definately should be used if Processor\% Processor Time\(_Total) is maxing at 100% to assess the effect of the SQL Server process on the processor Process Working Set sqlservr If the Memory\Available bytes counter is decreaing this counter can be run to indicate if the process is consuming larger and larger amounts of RAM. Process(instance)\Working Set measures the size of the working set for each process, which indicates the number of allocated pages the process can address without generating a page fault. Process Working Set msmdsrv If the Memory\Available bytes counter is decreaing this counter can be run to indicate if the process is consuming larger and larger amounts of RAM. Process(instance)\Working Set measures the size of the working set for each process, which indicates the number of allocated pages the process can address without generating a page fault. Processor % Processor Time _Total and individual cores measures the total utilization of your processor by all running processes. If multi-proc then be mindful only an average is provided Processor % Privileged Time _Total To see how the OS is handling basic IO requests. If kernel mode utilization is high, your machine is likely underpowered as it's too busy handling basic OS housekeeping functions to be able to effectively run other applications. Processor % User Time _Total To see how the applications is interacting from a processor perspective, a high percentage utilisation determine that the server is dealing with too many apps and may require increasing thje hardware or scaling out Processor Interrupts/sec _Total  The average rate, in incidents per second, at which the processor received and serviced hardware interrupts. Shoulr be consistant over time but a sudden unexplained increase could indicate a device malfunction which can be confirmed using the System\Context Switches/sec counter Memory Pages/sec N/A Indicates the rate at which pages are read from or written to disk to resolve hard page faults. This counter is a primary indicator of the kinds of faults that cause system-wide delays, this is the primary counter to watch for indication of possible insufficient RAM to meet your server's needs. A good idea here is to configure a perfmon alert that triggers when the number of pages per second exceeds 50 per paging disk on your system. May also want to see the configuration of the page file on the Server Memory Available Mbytes N/A is the amount of physical memory, in bytes, available to processes running on the computer. if this counter is greater than 10% of the actual RAM in your machine then you probably have more than enough RAM. monitor it regularly to see if any downward trend develops, and set an alert to trigger if it drops below 2% of the installed RAM. Physical Disk Disk Transfers/sec for each physical disk If it goes above 10 disk I/Os per second then you've got poor response time for your disk. Physical Disk Idle Time _total If Disk Transfers/sec is above  25 disk I/Os per second use this counter. which measures the percent time that your hard disk is idle during the measurement interval, and if you see this counter fall below 20% then you've likely got read/write requests queuing up for your disk which is unable to service these requests in a timely fashion. Physical Disk Disk queue legnth For the OLAP and SQL physical disk A value that is consistently less than 2 means that the disk system is handling the IO requests against the physical disk Network Interface Bytes Total/sec For the NIC Should be monitored over a period of time to see if there is anb increase/decrease in network utilisation Network Interface Current Bandwidth For the NIC is an estimate of the current bandwidth of the network interface in bits per second (BPS). MSAS 2005: Memory Memory Limit High KB N/A Shows (as a percentage) the high memory limit configured for SSAS in C:\Program Files\Microsoft SQL Server\MSAS10.MSSQLSERVER\OLAP\Config\msmdsrv.ini MSAS 2005: Memory Memory Limit Low KB N/A Shows (as a percentage) the low memory limit configured for SSAS in C:\Program Files\Microsoft SQL Server\MSAS10.MSSQLSERVER\OLAP\Config\msmdsrv.ini MSAS 2005: Memory Memory Usage KB N/A Displays the memory usage of the server process. MSAS 2005: Memory File Store KB N/A Displays the amount of memory that is reserved for the Cache. Note if total memory limit in the msmdsrv.ini is set to 0, no memory is reserved for the cache MSAS 2005: Storage Engine Query Queries from Cache Direct / sec N/A Displays the rate of queries answered from the cache directly MSAS 2005: Storage Engine Query Queries from Cache Filtered / Sec N/A Displays the Rate of queries answered by filtering existing cache entry. MSAS 2005: Storage Engine Query Queries from File / Sec N/A Displays the Rate of queries answered from files. MSAS 2005: Storage Engine Query Average time /query N/A Displays the average time of a query MSAS 2005: Connection Current connections N/A Displays the number of connections against the SSAS instance MSAS 2005: Connection Requests / sec N/A Displays the rate of query requests per second MSAS 2005: Locks Current Lock Waits N/A Displays thhe number of connections waiting on a lock MSAS 2005: Threads Query Pool job queue Length N/A The number of queries in the job queue MSAS 2005:Proc Aggregations Temp file bytes written/sec N/A Shows the number of bytes of data processed in a temporary file MSAS 2005:Proc Aggregations Temp file rows written/sec N/A Shows the number of bytes of data processed in a temporary file 

  Read the article

• How to solve exception_priv _instruction exception while running destop project? [on hold]

  - by Haritha

  While running desktop project im getting exception_priv _instruction how to solve this??? while running this page is coming # # A fatal error has been detected by the Java Runtime Environment: # # EXCEPTION_PRIV_INSTRUCTION (0xc0000096) at pc=0x02f5a92b, pid=3012, tid=3104 # # JRE version: 7.0-b147 # Java VM: Java HotSpot(TM) Client VM (21.0-b17 mixed mode, sharing windows-x86 ) # Problematic frame: # C 0x02f5a92b # # Failed to write core dump. Minidumps are not enabled by default on client versions of Windows # # If you would like to submit a bug report, please visit: # http://bugreport.sun.com/bugreport/crash.jsp # The crash happened outside the Java Virtual Machine in native code. # See problematic frame for where to report the bug. # --------------- T H R E A D --------------- Current thread (0x02f5a800): JavaThread "LWJGL Application" [_thread_in_native, id=3104, stack(0x076f0000,0x07740000)] siginfo: ExceptionCode=0xc0000096 Registers: EAX=0x000df4f0, EBX=0x32afc180, ECX=0x000df4f0, EDX=0x00000020 ESP=0x0773f768, EBP=0x0773f790, ESI=0x32afc180, EDI=0x02f5a800 EIP=0x02f5a92b, EFLAGS=0x00010206 Top of Stack: (sp=0x0773f768) 0x0773f768: 02bd429c 02bd429c 0773f770 32afc180 0x0773f778: 0773f7b8 32b022c8 00000000 32afc180 0x0773f788: 00000000 0773f7a0 0773f7dc 00943187 0x0773f798: 229ec1c0 00948839 69081736 00000000 0x0773f7a8: 089b0048 00000000 00000014 00001406 0x0773f7b8: 00000002 0773f7bc 32afbeb0 0773f7f8 0x0773f7c8: 32b022c8 00000000 32afbf00 0773f7a0 0x0773f7d8: 0773f7f0 0773f81c 00943187 69081736 Instructions: (pc=0x02f5a92b) 0x02f5a90b: 00 43 00 00 00 00 f0 bc 02 e8 00 e9 22 40 f7 73 0x02f5a91b: 07 85 a5 94 00 90 f7 73 07 50 cc a0 6d d8 49 c0 0x02f5a92b: 6d 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x02f5a93b: 00 00 00 00 00 00 00 00 00 08 80 3d 37 00 00 00 Register to memory mapping: EAX=0x000df4f0 is an unknown value EBX=0x32afc180 is an oop {method} - klass: {other class} ECX=0x000df4f0 is an unknown value EDX=0x00000020 is an unknown value ESP=0x0773f768 is pointing into the stack for thread: 0x02f5a800 EBP=0x0773f790 is pointing into the stack for thread: 0x02f5a800 ESI=0x32afc180 is an oop {method} - klass: {other class} EDI=0x02f5a800 is a thread Stack: [0x076f0000,0x07740000], sp=0x0773f768, free space=317k Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code) C 0x02f5a92b j org.lwjgl.opengl.GL11.glVertexPointer(IILjava/nio/FloatBuffer;)V+48 j com.badlogic.gdx.backends.lwjgl.LwjglGL10.glVertexPointer(IIILjava/nio/Buffer;)V+53 j com.badlogic.gdx.graphics.glutils.VertexArray.bind()V+149 j com.badlogic.gdx.graphics.Mesh.bind()V+25 j com.badlogic.gdx.graphics.Mesh.render(IIIZ)V+32 j com.badlogic.gdx.graphics.Mesh.render(III)V+8 j com.badlogic.gdx.graphics.g2d.SpriteBatch.flush()V+197 j com.badlogic.gdx.graphics.g2d.SpriteBatch.switchTexture(Lcom/badlogic/gdx/graphics/Texture;)V+1 j com.badlogic.gdx.graphics.g2d.SpriteBatch.draw(Lcom/badlogic/gdx/graphics/Texture;FFFF)V+33 j sevenseas.game.WorldRenderer.drawBob()V+54 j sevenseas.game.WorldRenderer.render()V+12 j sevenseas.game.GameClass.render(F)V+38 j com.badlogic.gdx.Game.render()V+19 j com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop()V+642 j com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run()V+27 v ~StubRoutines::call_stub V [jvm.dll+0x122c7e] V [jvm.dll+0x1c9c0e] V [jvm.dll+0x122e73] V [jvm.dll+0x122ed7] V [jvm.dll+0xccd1f] V [jvm.dll+0x14433f] V [jvm.dll+0x171549] C [msvcr100.dll+0x5c6de] endthreadex+0x3a C [msvcr100.dll+0x5c788] endthreadex+0xe4 C [kernel32.dll+0xb713] GetModuleFileNameA+0x1b4 Java frames: (J=compiled Java code, j=interpreted, Vv=VM code) j org.lwjgl.opengl.GL11.nglVertexPointer(IIIJJ)V+0 j org.lwjgl.opengl.GL11.glVertexPointer(IILjava/nio/FloatBuffer;)V+48 j com.badlogic.gdx.backends.lwjgl.LwjglGL10.glVertexPointer(IIILjava/nio/Buffer;)V+53 j com.badlogic.gdx.graphics.glutils.VertexArray.bind()V+149 j com.badlogic.gdx.graphics.Mesh.bind()V+25 j com.badlogic.gdx.graphics.Mesh.render(IIIZ)V+32 j com.badlogic.gdx.graphics.Mesh.render(III)V+8 j com.badlogic.gdx.graphics.g2d.SpriteBatch.flush()V+197 j com.badlogic.gdx.graphics.g2d.SpriteBatch.switchTexture(Lcom/badlogic/gdx/graphics/Texture;)V+1 j com.badlogic.gdx.graphics.g2d.SpriteBatch.draw(Lcom/badlogic/gdx/graphics/Texture;FFFF)V+33 j sevenseas.game.WorldRenderer.drawBob()V+54 j sevenseas.game.WorldRenderer.render()V+12 j sevenseas.game.GameClass.render(F)V+38 j com.badlogic.gdx.Game.render()V+19 j com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop()V+642 j com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run()V+27 v ~StubRoutines::call_stub --------------- P R O C E S S --------------- Java Threads: ( => current thread ) 0x003d6c00 JavaThread "DestroyJavaVM" [_thread_blocked, id=3240, stack(0x008c0000,0x00910000)] =>0x02f5a800 JavaThread "LWJGL Application" [_thread_in_native, id=3104, stack(0x076f0000,0x07740000)] 0x02bcf000 JavaThread "Service Thread" daemon [_thread_blocked, id=2612, stack(0x02e00000,0x02e50000)] 0x02bc1000 JavaThread "C1 CompilerThread0" daemon [_thread_blocked, id=2776, stack(0x02db0000,0x02e00000)] 0x02bbf400 JavaThread "Attach Listener" daemon [_thread_blocked, id=2448, stack(0x02d60000,0x02db0000)] 0x02bbe000 JavaThread "Signal Dispatcher" daemon [_thread_blocked, id=1764, stack(0x02d10000,0x02d60000)] 0x02bb8000 JavaThread "Finalizer" daemon [_thread_blocked, id=3864, stack(0x02cc0000,0x02d10000)] 0x02bb3400 JavaThread "Reference Handler" daemon [_thread_blocked, id=2424, stack(0x02c70000,0x02cc0000)] Other Threads: 0x02bb1800 VMThread [stack: 0x02c20000,0x02c70000] [id=3076] 0x02bd1000 WatcherThread [stack: 0x02e50000,0x02ea0000] [id=3276] VM state:not at safepoint (normal execution) VM Mutex/Monitor currently owned by a thread: None Heap def new generation total 4928K, used 2571K [0x229c0000, 0x22f10000, 0x27f10000) eden space 4416K, 46% used [0x229c0000, 0x22bc2e38, 0x22e10000) from space 512K, 100% used [0x22e90000, 0x22f10000, 0x22f10000) to space 512K, 0% used [0x22e10000, 0x22e10000, 0x22e90000) tenured generation total 10944K, used 634K [0x27f10000, 0x289c0000, 0x329c0000) the space 10944K, 5% used [0x27f10000, 0x27faea60, 0x27faec00, 0x289c0000) compacting perm gen total 12288K, used 1655K [0x329c0000, 0x335c0000, 0x369c0000) the space 12288K, 13% used [0x329c0000, 0x32b5dc58, 0x32b5de00, 0x335c0000) ro space 10240K, 42% used [0x369c0000, 0x36dfc660, 0x36dfc800, 0x373c0000) rw space 12288K, 53% used [0x373c0000, 0x37a38180, 0x37a38200, 0x37fc0000) Code Cache [0x00940000, 0x009d8000, 0x02940000) total_blobs=305 nmethods=80 adapters=158 free_code_cache=32183Kb largest_free_block=32955904 Dynamic libraries: 0x00400000 - 0x0042f000 C:\Program Files\Java\jre7\bin\javaw.exe 0x7c900000 - 0x7c9af000 C:\WINDOWS\system32\ntdll.dll 0x7c800000 - 0x7c8f6000 C:\WINDOWS\system32\kernel32.dll 0x77dd0000 - 0x77e6b000 C:\WINDOWS\system32\ADVAPI32.dll 0x77e70000 - 0x77f02000 C:\WINDOWS\system32\RPCRT4.dll 0x77fe0000 - 0x77ff1000 C:\WINDOWS\system32\Secur32.dll 0x7e410000 - 0x7e4a1000 C:\WINDOWS\system32\USER32.dll 0x77f10000 - 0x77f59000 C:\WINDOWS\system32\GDI32.dll 0x773d0000 - 0x774d3000 C:\WINDOWS\WinSxS\x86_Microsoft.Windows.Common-Controls_6595b64144ccf1df_6.0.2600.5512_x-ww_35d4ce83\COMCTL32.dll 0x77c10000 - 0x77c68000 C:\WINDOWS\system32\msvcrt.dll 0x77f60000 - 0x77fd6000 C:\WINDOWS\system32\SHLWAPI.dll 0x76390000 - 0x763ad000 C:\WINDOWS\system32\IMM32.DLL 0x629c0000 - 0x629c9000 C:\WINDOWS\system32\LPK.DLL 0x74d90000 - 0x74dfb000 C:\WINDOWS\system32\USP10.dll 0x78aa0000 - 0x78b5e000 C:\Program Files\Java\jre7\bin\msvcr100.dll 0x6d940000 - 0x6dc61000 C:\Program Files\Java\jre7\bin\client\jvm.dll 0x71ad0000 - 0x71ad9000 C:\WINDOWS\system32\WSOCK32.dll 0x71ab0000 - 0x71ac7000 C:\WINDOWS\system32\WS2_32.dll 0x71aa0000 - 0x71aa8000 C:\WINDOWS\system32\WS2HELP.dll 0x76b40000 - 0x76b6d000 C:\WINDOWS\system32\WINMM.dll 0x76bf0000 - 0x76bfb000 C:\WINDOWS\system32\PSAPI.DLL 0x6d8d0000 - 0x6d8dc000 C:\Program Files\Java\jre7\bin\verify.dll 0x6d370000 - 0x6d390000 C:\Program Files\Java\jre7\bin\java.dll 0x6d920000 - 0x6d933000 C:\Program Files\Java\jre7\bin\zip.dll 0x6cec0000 - 0x6cf42000 C:\Documents and Settings\7stl0225\Local Settings\Temp\libgdx7stl0225\37fe1abc\gdx.dll 0x10000000 - 0x1004c000 C:\Documents and Settings\7stl0225\Local Settings\Temp\libgdx7stl0225\52d76f2b\lwjgl.dll 0x5ed00000 - 0x5edcc000 C:\WINDOWS\system32\OPENGL32.dll 0x68b20000 - 0x68b40000 C:\WINDOWS\system32\GLU32.dll 0x73760000 - 0x737ab000 C:\WINDOWS\system32\DDRAW.dll 0x73bc0000 - 0x73bc6000 C:\WINDOWS\system32\DCIMAN32.dll 0x77c00000 - 0x77c08000 C:\WINDOWS\system32\VERSION.dll 0x070b0000 - 0x07115000 C:\DOCUME~1\7stl0225\LOCALS~1\Temp\libgdx7stl0225\52d76f2b\OpenAL32.dll 0x7c9c0000 - 0x7d1d7000 C:\WINDOWS\system32\SHELL32.dll 0x774e0000 - 0x7761d000 C:\WINDOWS\system32\ole32.dll 0x5ad70000 - 0x5ada8000 C:\WINDOWS\system32\uxtheme.dll 0x76fd0000 - 0x7704f000 C:\WINDOWS\system32\CLBCATQ.DLL 0x77050000 - 0x77115000 C:\WINDOWS\system32\COMRes.dll 0x77120000 - 0x771ab000 C:\WINDOWS\system32\OLEAUT32.dll 0x73f10000 - 0x73f6c000 C:\WINDOWS\system32\dsound.dll 0x76c30000 - 0x76c5e000 C:\WINDOWS\system32\WINTRUST.dll 0x77a80000 - 0x77b15000 C:\WINDOWS\system32\CRYPT32.dll 0x77b20000 - 0x77b32000 C:\WINDOWS\system32\MSASN1.dll 0x76c90000 - 0x76cb8000 C:\WINDOWS\system32\IMAGEHLP.dll 0x72d20000 - 0x72d29000 C:\WINDOWS\system32\wdmaud.drv 0x72d10000 - 0x72d18000 C:\WINDOWS\system32\msacm32.drv 0x77be0000 - 0x77bf5000 C:\WINDOWS\system32\MSACM32.dll 0x77bd0000 - 0x77bd7000 C:\WINDOWS\system32\midimap.dll 0x73ee0000 - 0x73ee4000 C:\WINDOWS\system32\KsUser.dll 0x755c0000 - 0x755ee000 C:\WINDOWS\system32\msctfime.ime 0x69000000 - 0x691a9000 C:\WINDOWS\system32\sisgl.dll 0x73b30000 - 0x73b45000 C:\WINDOWS\system32\mscms.dll 0x73000000 - 0x73026000 C:\WINDOWS\system32\WINSPOOL.DRV 0x66e90000 - 0x66ed1000 C:\WINDOWS\system32\icm32.dll 0x07760000 - 0x0778d000 C:\Program Files\WordWeb\WHook.dll 0x74c80000 - 0x74cac000 C:\WINDOWS\system32\OLEACC.dll 0x76080000 - 0x760e5000 C:\WINDOWS\system32\MSVCP60.dll VM Arguments: jvm_args: -Dfile.encoding=Cp1252 java_command: sevenseas.game.MainDesktop Launcher Type: SUN_STANDARD Environment Variables: PATH=C:/Program Files/Java/jre7/bin/client;C:/Program Files/Java/jre7/bin;C:/Program Files/Java/jre7/lib/i386;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\Program Files\Java\jdk1.7.0\bin;C:\eclipse; USERNAME=7stl0225 OS=Windows_NT PROCESSOR_IDENTIFIER=x86 Family 15 Model 4 Stepping 1, GenuineIntel --------------- S Y S T E M --------------- OS: Windows XP Build 2600 Service Pack 3 CPU:total 1 (1 cores per cpu, 1 threads per core) family 15 model 4 stepping 1, cmov, cx8, fxsr, mmx, sse, sse2, sse3 Memory: 4k page, physical 2031088k(939252k free), swap 3969920k(3011396k free) vm_info: Java HotSpot(TM) Client VM (21.0-b17) for windows-x86 JRE (1.7.0-b147), built on Jun 27 2011 02:25:52 by "java_re" with unknown MS VC++:1600 time: Sat Oct 26 12:35:14 2013 elapsed time: 0 seconds

  Read the article

• Why you need to learn async in .NET

  - by PSteele

  I had an opportunity to teach a quick class yesterday about what’s new in .NET 4.0.  One of the topics was the TPL (Task Parallel Library) and how it can make async programming easier.  I also stressed that this is the direction Microsoft is going with for C# 5.0 and learning the TPL will greatly benefit their understanding of the new async stuff.  We had a little time left over and I was able to show some code that uses the Async CTP to accomplish some stuff, but it wasn’t a simple demo that you could jump in to and understand so I thought I’d thrown one together and put it in a blog post. The entire solution file with all of the sample projects is located here. A Simple Example Let’s start with a super-simple example (WindowsApplication01 in the solution). I’ve got a form that displays a label and a button.  When the user clicks the button, I want to start displaying the current time for 15 seconds and then stop. What I’d like to write is this: lblTime.ForeColor = Color.Red; for (var x = 0; x < 15; x++) { lblTime.Text = DateTime.Now.ToString("HH:mm:ss"); Thread.Sleep(1000); } lblTime.ForeColor = SystemColors.ControlText; (Note that I also changed the label’s color while counting – not quite an ILM-level effect, but it adds something to the demo!) As I’m sure most of my readers are aware, you can’t write WinForms code this way.  WinForms apps, by default, only have one thread running and it’s main job is to process messages from the windows message pump (for a more thorough explanation, see my Visual Studio Magazine article on multithreading in WinForms).  If you put a Thread.Sleep in the middle of that code, your UI will be locked up and unresponsive for those 15 seconds.  Not a good UX and something that needs to be fixed.  Sure, I could throw an “Application.DoEvents()” in there, but that’s hacky. The Windows Timer Then I think, “I can solve that.  I’ll use the Windows Timer to handle the timing in the background and simply notify me when the time has changed”.  Let’s see how I could accomplish this with a Windows timer (WindowsApplication02 in the solution): public partial class Form1 : Form { private readonly Timer clockTimer; private int counter;   public Form1() { InitializeComponent(); clockTimer = new Timer {Interval = 1000}; clockTimer.Tick += UpdateLabel; }   private void UpdateLabel(object sender, EventArgs e) { lblTime.Text = DateTime.Now.ToString("HH:mm:ss"); counter++; if (counter == 15) { clockTimer.Enabled = false; lblTime.ForeColor = SystemColors.ControlText; } }   private void cmdStart_Click(object sender, EventArgs e) { lblTime.ForeColor = Color.Red; counter = 0; clockTimer.Start(); } } Holy cow – things got pretty complicated here.  I use the timer to fire off a Tick event every second.  Inside there, I can update the label.  Granted, I can’t use a simple for/loop and have to maintain a global counter for the number of iterations.  And my “end” code (when the loop is finished) is now buried inside the bottom of the Tick event (inside an “if” statement).  I do, however, get a responsive application that doesn’t hang or stop repainting while the 15 seconds are ticking away. But doesn’t .NET have something that makes background processing easier? The BackgroundWorker Next I try .NET’s BackgroundWorker component – it’s specifically designed to do processing in a background thread (leaving the UI thread free to process the windows message pump) and allows updates to be performed on the main UI thread (WindowsApplication03 in the solution): public partial class Form1 : Form { private readonly BackgroundWorker worker;   public Form1() { InitializeComponent(); worker = new BackgroundWorker {WorkerReportsProgress = true}; worker.DoWork += StartUpdating; worker.ProgressChanged += UpdateLabel; worker.RunWorkerCompleted += ResetLabelColor; }   private void StartUpdating(object sender, DoWorkEventArgs e) { var workerObject = (BackgroundWorker) sender; for (int x = 0; x < 15; x++) { workerObject.ReportProgress(0); Thread.Sleep(1000); } }   private void UpdateLabel(object sender, ProgressChangedEventArgs e) { lblTime.Text = DateTime.Now.ToString("HH:mm:ss"); }   private void ResetLabelColor(object sender, RunWorkerCompletedEventArgs e) { lblTime.ForeColor = SystemColors.ControlText; }   private void cmdStart_Click(object sender, EventArgs e) { lblTime.ForeColor = Color.Red; worker.RunWorkerAsync(); } } Well, this got a little better (I think).  At least I now have my simple for/next loop back.  Unfortunately, I’m still dealing with event handlers spread throughout my code to co-ordinate all of this stuff in the right order. Time to look into the future. The async way Using the Async CTP, I can go back to much simpler code (WindowsApplication04 in the solution): private async void cmdStart_Click(object sender, EventArgs e) { lblTime.ForeColor = Color.Red; for (var x = 0; x < 15; x++) { lblTime.Text = DateTime.Now.ToString("HH:mm:ss"); await TaskEx.Delay(1000); } lblTime.ForeColor = SystemColors.ControlText; } This code will run just like the Timer or BackgroundWorker versions – fully responsive during the updates – yet is way easier to implement.  In fact, it’s almost a line-for-line copy of the original version of this code.  All of the async plumbing is handled by the compiler and the framework.  My code goes back to representing the “what” of what I want to do, not the “how”. I urge you to download the Async CTP.  All you need is .NET 4.0 and Visual Studio 2010 sp1 – no need to set up a virtual machine with the VS2011 beta (unless, of course, you want to dive right in to the C# 5.0 stuff!).  Starting playing around with this today and see how much easier it will be in the future to write async-enabled applications.

  Read the article

• Getting problem in collision detection in Java Game

  - by chetans

  Hi I am developing Spaceship Game in which i am getting problem in collision detection of moving images Game has a spaceship and number of asteroids(obstacles) i want to detect the collision between them How can i do this?`package Game; import java.applet.Applet; import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Image; import java.awt.MediaTracker; import java.awt.event.KeyEvent; import java.awt.event.KeyListener; import java.net.MalformedURLException; import java.net.URL; public class ThreadInApplet extends Applet implements KeyListener { private static final long serialVersionUID = 1L; Image[] asteroidImage; Image spaceshipImage; int[] XPosObst,YPosObst; int numberOfObstacles=0,XPosOfSpaceship,YPosOfSpaceship; int spaceButtnCntr=0,noOfObstaclesLevel=20; boolean gameStart=false,collideUp=false,collideDown=false,collideLeft=false,collideRight=false; private Image offScreenImage; private Dimension offScreenSize,d; private Graphics offScreenGraphics; int speedObstacles=1; String spaceshipImagePath="images/spaceship.png",obstacleImagepath="images/asteroid.png"; String buttonToStart="Press Space to start"; public void init() { try { asteroidImage=new Image[noOfObstaclesLevel]; XPosObst=new int[noOfObstaclesLevel]; YPosObst=new int[noOfObstaclesLevel]; XPosOfSpaceship=getWidth()/2-35; YPosOfSpaceship=getHeight()-100; spaceshipImage=getImage(new URL(getCodeBase(),spaceshipImagePath)); for(int i=0;i<noOfObstaclesLevel;i++) { asteroidImage[i]=getImage(new URL(getCodeBase(),obstacleImagepath)); XPosObst[i]=(int) (Math.random()*700); YPosObst[i]=0; } MediaTracker tracker = new MediaTracker (this); for(int i=0;i<noOfObstaclesLevel;i++) { tracker.addImage (asteroidImage[i], 0); } } catch (MalformedURLException e) { e.printStackTrace(); } setBackground(Color.black); addKeyListener(this); } public void paint(Graphics g) { g.setColor(Color.white); if(gameStart==false) { g.drawString(buttonToStart, (getWidth()/2)-60, getHeight()/2); } g.drawString("HEADfitted Solutions Pvt.Ltd.", (getWidth()/2)-80, getHeight()-20); for(int n=0;n<numberOfObstacles;n++) { if(n>0) g.drawImage(asteroidImage[n],XPosObst[n],YPosObst[n],this); } g.drawImage(spaceshipImage,XPosOfSpaceship,YPosOfSpaceship,this); } @SuppressWarnings("deprecation") public void update(Graphics g) { d = size(); if((offScreenImage == null) || (d.width != offScreenSize.width) || (d.height != offScreenSize.height)) { offScreenImage = createImage(d.width, d.height); offScreenSize = d; offScreenGraphics = offScreenImage.getGraphics(); } offScreenGraphics.clearRect(0, 0, d.width, d.height); paint(offScreenGraphics); g.drawImage(offScreenImage, 0, 0, null); } public void keyReleased(KeyEvent arg0){} public void keyTyped(KeyEvent arg0) {} Thread mainThread=new Thread() { synchronized public void run () { try { //System.out.println("in main thread"); if (gameStart==true) { moveObstacles.start(); if(collide()==false) { createObsThread.start(); } } } catch (Exception e) { e.printStackTrace(); } } }; Thread createObsThread=new Thread() { synchronized public void run () { if (spaceButtnCntr==1) { if (collide()==false) { for(int g=0;g<noOfObstaclesLevel;g++) { try { sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } numberOfObstacles++; } } } } }; Thread moveObstacles=new Thread() // Moving Obstacle images downwards after every 10 ms { synchronized public void run () { while(YPosObst[19]!=600) { if (collide()==false) { //createObsThread.start(); for(int l=0;l } repaint(); try { sleep(10); } catch (InterruptedException e) { e.printStackTrace(); } } } } }; public void keyPressed(KeyEvent e) { if(e.getKeyCode()==32) { gameStart=true; spaceButtnCntr++; if (spaceButtnCntr==1) { mainThread.start(); } } if(gameStart==true) { if(e.getKeyCode()==37 && collideLeft==false)//Spaceship movement left { new Thread () { synchronized public void run () { XPosOfSpaceship-=10; repaint(); } }.start(); } if(e.getKeyCode()==38 && collideUp==false)//Spaceship movement up { new Thread () { synchronized public void run () { YPosOfSpaceship-=10; repaint(); } }.start(); } if(e.getKeyCode()==39 && collideRight==false)//Spaceship movement right { new Thread () { synchronized public void run () { XPosOfSpaceship+=10; repaint(); } }.start(); } if(e.getKeyCode()==40 && collideDown==false)//Spaceship movement down { new Thread () { synchronized public void run () { YPosOfSpaceship+=10; repaint(); } }.start(); } } } /*public boolean collide() { int x0, y0, w0, h0, x2, y2, w2, h2; x0=XPosOfSpaceship; y0=YPosOfSpaceship; h0=spaceshipImage.getHeight(null); w0=spaceshipImage.getWidth(null); for(int i=0;i<20;i++) { x2=XPosObst[i]; y2=YPosObst[i]; h2=asteroidImage[i].getHeight(null); w2=asteroidImage[i].getWidth(null); if ((x0 > (x2 + w2)) || ((x0 + w0) < x2)) return false; System.out.println(x2+" "+y2+" "+h2+" "+w2); if ((y0 > (y2 + h2)) || ((y0 + h0) < y2)) return false; } return true; }*/ public boolean collide() { int x1,y1,x2,y2,x3,y3,x4,y4; //coordinates of obstacles int a1,b1,a2,b2,a3,b3,a4,b4; //coordinates of spaceship a1 =XPosOfSpaceship; b1=YPosOfSpaceship; a2=a1+spaceshipImage.getWidth(this); b2=b1; a3=a1; b3=b1+spaceshipImage.getHeight(this); a4=a2; b4=b3; for(int a=0;a if(x1>=a1 && x1<=a2 && x1<=b3 && x1>=b1) return (true); if(x2>=a1 && x2<=a2 && x2<=b3 && x2>=b1) return(true); //********checking asteroid touch spaceship from up direction******** if(y3==b1 && x4>=a1 && x4<=a2) { collideUp = true; return(true); } if(y3==b1 && x3>=a1 && x3<=a2) { collideUp = true; return(true); } //********checking asteroid touch spaceship from left direction****** if(x2==a1 && y4>=b1 && y4<=b3) { collideLeft=true; return(true); } if(x2==a1 && y2>=b1 && y2<=b3) { collideLeft=true; return(true); } //********checking asteroid touch spaceship from right direction***** if(x1==a2 && y3>=b2 && y3<=b4) { collideRight=true; return(true); } if(x1==a2 && y1>=b2 && y1<=b4) { collideRight=true; return(true); } //********checking asteroid touch spaceship from down direction***** if(y1==b3 && x2>=a3 && x2<=a4) { collideDown=true; return(true); } if(y1==b3 && x1>=a3 && x1<=a4) { collideDown=true; return(true); } else { collideUp=false; collideDown=false; collideLeft=false; collideRight=false; } } return(false); } } `

  Read the article

• OpenGL ES 2.0: Using VBOs?

  - by Bunkai.Satori

  OpenGL VBOs (vertex buffer objects) have been developed to improve performance of OpenGL (OpenGL ES 2.0 in my case). The logic is that with the help of VBOs, the data does not need to be copied from client memory to graphics card on per frame basis. However, as I see it, the game scene changes continuously: position of objects change, their scaling and rotating change, they get animated, they explode, they get spawn or disappear. In such highly dynamic environment, such as computer game scene is, what is the point of using VBOs, if the VBOs would need to be constructed on per-frame basis anyway? Can you please help me to understand how to practically take beneif of VBOs in computer games? Can there be more vertex based VBOs (say one per one object) or there must be always exactly only one VBO present for each draw cycle?

  Read the article

• ASP.NET WebAPI Security 2: Identity Architecture

  - by Your DisplayName here!

  Pedro has beaten me to the punch with a detailed post (and diagram) about the WebAPI hosting architecture. So go read his post first, then come back so we can have a closer look at what that means for security. The first important takeaway is that WebAPI is hosting independent-  currently it ships with two host integration implementations – one for ASP.NET (aka web host) and WCF (aka self host). Pedro nicely shows the integration into the web host. Self hosting is not done yet so we will mainly focus on the web hosting case and I will point out security related differences when they exist. The interesting part for security (amongst other things of course) is the HttpControllerHandler (see Pedro’s diagram) – this is where the host specific representation of an HTTP request gets converted to the WebAPI abstraction (called HttpRequestMessage). The ConvertRequest method does the following: Create a new HttpRequestMessage. Copy URI, method and headers from the HttpContext. Copies HttpContext.User to the Properties<string, object> dictionary on the HttpRequestMessage. The key used for that can be found on HttpPropertyKeys.UserPrincipalKey (which resolves to “MS_UserPrincipal”). So the consequence is that WebAPI receives whatever IPrincipal has been set by the ASP.NET pipeline (in the web hosting case). Common questions are: Are there situations where is property does not get set? Not in ASP.NET – the DefaultAuthenticationModule in the HTTP pipeline makes sure HttpContext.User (and Thread.CurrentPrincipal – more on that later) are always set. Either to some authenticated user – or to an anonymous principal. This may be different in other hosting environments (again more on that later). Why so generic? Keep in mind that WebAPI is hosting independent and may run on a host that materializes identity completely different compared to ASP.NET (or .NET in general). This gives them a way to evolve the system in the future. How does WebAPI code retrieve the current client identity? HttpRequestMessage has an extension method called GetUserPrincipal() which returns the property as an IPrincipal. A quick look at self hosting shows that the moral equivalent of HttpControllerHandler.ConvertRequest() is HttpSelfHostServer.ProcessRequestContext(). Here the principal property gets only set when the host is configured for Windows authentication (inconsisteny). Do I like that? Well – yes and no. Here are my thoughts: I like that it is very straightforward to let WebAPI inherit the client identity context of the host. This might not always be what you want – think of an ASP.NET app that consists of UI and APIs – the UI might use Forms authentication, the APIs token based authentication. So it would be good if the two parts would live in a separate security world. It makes total sense to have this generic hand off point for identity between the host and WebAPI. It also makes total sense for WebAPI plumbing code (especially handlers) to use the WebAPI specific identity abstraction. But – c’mon we are running on .NET. And the way .NET represents identity is via IPrincipal/IIdentity. That’s what every .NET developer on this planet is used to. So I would like to see a User property of type IPrincipal on ApiController. I don’t like the fact that Thread.CurrentPrincipal is not populated. T.CP is a well established pattern as a one stop shop to retrieve client identity on .NET.  That makes a lot of sense – even if the name is misleading at best. There might be existing library code you want to call from WebAPI that makes use of T.CP (e.g. PrincipalPermission, or a simple .Name or .IsInRole()). Having the client identity as an ambient property is useful for code that does not have access to the current HTTP request (for calling GetUserPrincipal()). I don’t like the fact that that the client identity conversion from host to WebAPI is inconsistent. This makes writing security plumbing code harder. I think the logic should always be: If the host has a client identity representation, copy it. If not, set an anonymous principal on the request message. Btw – please don’t annoy me with the “but T.CP is static, and static is bad for testing” chant. T.CP is a getter/setter and, in fact I find it beneficial to be able to set different security contexts in unit tests before calling in some logic. And, in case you have wondered – T.CP is indeed thread static (and the name comes from a time where a logical operation was bound to a thread – which is not true anymore). But all thread creation APIs in .NET actually copy T.CP to the new thread they create. This is the case since .NET 2.0 and is certainly an improvement compared to how Win32 does things. So to sum it up: The host plumbing copies the host client identity to WebAPI (this is not perfect yet, but will surely be improved). or in other words: The current WebAPI bits don’t ship with any authentication plumbing, but solely use whatever authentication (and thus client identity) is set up by the host. WebAPI developers can retrieve the client identity from the HttpRequestMessage. Hopefully my proposed changes around T.CP and the User property on ApiController will be added. In the next post, I will detail how to add WebAPI specific authentication support, e.g. for Basic Authentication and tokens. This includes integrating the notion of claims based identity. After that we will look at the built-in authorization bits and how to improve them as well. Stay tuned.

  Read the article

• Geometry instancing in OpenGL ES 2.0

  - by seahorse

  I am planning to do geometry instancing in OpenGL ES 2.0 Basically I plan to render the same geometry(a chair) maybe 1000 times in my scene. What is the best way to do this in OpenGL ES 2.0? I am considering passing model view mat4 as an attribute. Since attributes are per vertex data do I need to pass this same mat4, three times for each vertex of the same triangle(since modelview remains constant across vertices of the triangle). That would amount to a lot of extra data sent to the GPU( 2 extra vertices*16 floats*(Number of triangles) amount of extra data). Or should I be sending the mat4 only once per triangle?But how is that possible using attributes since attributes are defined as "per vertex" data? What is the best and efficient way to do instancing in OpenGL ES 2.0?

  Read the article

• Code Trivia #6

  - by João Angelo

  It’s time for yet another code trivia and it’s business as usual. What will the following program output to the console? using System; using System.Drawing; using System.Threading; class Program { [ThreadStatic] static Point Mark = new Point(1, 1); static void Main() { Thread.CurrentThread.Name = "A"; MoveMarkUp(); var helperThread = new Thread(MoveMarkUp) { Name = "B" }; helperThread.Start(); helperThread.Join(); } static void MoveMarkUp() { Mark.Y++; Console.WriteLine("{0}:{1}", Thread.CurrentThread.Name, Mark); } }

  Read the article

• PTLQueue : a scalable bounded-capacity MPMC queue

  - by Dave

  Title: Fast concurrent MPMC queue -- I've used the following concurrent queue algorithm enough that it warrants a blog entry. I'll sketch out the design of a fast and scalable multiple-producer multiple-consumer (MPSC) concurrent queue called PTLQueue. The queue has bounded capacity and is implemented via a circular array. Bounded capacity can be a useful property if there's a mismatch between producer rates and consumer rates where an unbounded queue might otherwise result in excessive memory consumption by virtue of the container nodes that -- in some queue implementations -- are used to hold values. A bounded-capacity queue can provide flow control between components. Beware, however, that bounded collections can also result in resource deadlock if abused. The put() and take() operators are partial and wait for the collection to become non-full or non-empty, respectively. Put() and take() do not allocate memory, and are not vulnerable to the ABA pathologies. The PTLQueue algorithm can be implemented equally well in C/C++ and Java. Partial operators are often more convenient than total methods. In many use cases if the preconditions aren't met, there's nothing else useful the thread can do, so it may as well wait via a partial method. An exception is in the case of work-stealing queues where a thief might scan a set of queues from which it could potentially steal. Total methods return ASAP with a success-failure indication. (It's tempting to describe a queue or API as blocking or non-blocking instead of partial or total, but non-blocking is already an overloaded concurrency term. Perhaps waiting/non-waiting or patient/impatient might be better terms). It's also trivial to construct partial operators by busy-waiting via total operators, but such constructs may be less efficient than an operator explicitly and intentionally designed to wait. A PTLQueue instance contains an array of slots, where each slot has volatile Turn and MailBox fields. The array has power-of-two length allowing mod/div operations to be replaced by masking. We assume sensible padding and alignment to reduce the impact of false sharing. (On x86 I recommend 128-byte alignment and padding because of the adjacent-sector prefetch facility). Each queue also has PutCursor and TakeCursor cursor variables, each of which should be sequestered as the sole occupant of a cache line or sector. You can opt to use 64-bit integers if concerned about wrap-around aliasing in the cursor variables. Put(null) is considered illegal, but the caller or implementation can easily check for and convert null to a distinguished non-null proxy value if null happens to be a value you'd like to pass. Take() will accordingly convert the proxy value back to null. An advantage of PTLQueue is that you can use atomic fetch-and-increment for the partial methods. We initialize each slot at index I with (Turn=I, MailBox=null). Both cursors are initially 0. All shared variables are considered "volatile" and atomics such as CAS and AtomicFetchAndIncrement are presumed to have bidirectional fence semantics. Finally T is the templated type. I've sketched out a total tryTake() method below that allows the caller to poll the queue. tryPut() has an analogous construction. Zebra stripping : alternating row colors for nice-looking code listings. See also google code "prettify" : https://code.google.com/p/google-code-prettify/ Prettify is a javascript module that yields the HTML/CSS/JS equivalent of pretty-print. -- pre:nth-child(odd) { background-color:#ff0000; } pre:nth-child(even) { background-color:#0000ff; } border-left: 11px solid #ccc; margin: 1.7em 0 1.7em 0.3em; background-color:#BFB; font-size:12px; line-height:65%; " // PTLQueue : Put(v) : // producer : partial method - waits as necessary assert v != null assert Mask = 1 && (Mask & (Mask+1)) == 0 // Document invariants // doorway step // Obtain a sequence number -- ticket // As a practical concern the ticket value is temporally unique // The ticket also identifies and selects a slot auto tkt = AtomicFetchIncrement (&PutCursor, 1) slot * s = &Slots[tkt & Mask] // waiting phase : // wait for slot's generation to match the tkt value assigned to this put() invocation. // The "generation" is implicitly encoded as the upper bits in the cursor // above those used to specify the index : tkt div (Mask+1) // The generation serves as an epoch number to identify a cohort of threads // accessing disjoint slots while s-Turn != tkt : Pause assert s-MailBox == null s-MailBox = v // deposit and pass message Take() : // consumer : partial method - waits as necessary auto tkt = AtomicFetchIncrement (&TakeCursor,1) slot * s = &Slots[tkt & Mask] // 2-stage waiting : // First wait for turn for our generation // Acquire exclusive "take" access to slot's MailBox field // Then wait for the slot to become occupied while s-Turn != tkt : Pause // Concurrency in this section of code is now reduced to just 1 producer thread // vs 1 consumer thread. // For a given queue and slot, there will be most one Take() operation running // in this section. // Consumer waits for producer to arrive and make slot non-empty // Extract message; clear mailbox; advance Turn indicator // We have an obvious happens-before relation : // Put(m) happens-before corresponding Take() that returns that same "m" for T v = s-MailBox if v != null : s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 // unlock slot to admit next producer and consumer return v Pause tryTake() : // total method - returns ASAP with failure indication for auto tkt = TakeCursor slot * s = &Slots[tkt & Mask] if s-Turn != tkt : return null T v = s-MailBox // presumptive return value if v == null : return null // ratify tkt and v values and commit by advancing cursor if CAS (&TakeCursor, tkt, tkt+1) != tkt : continue s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 return v The basic idea derives from the Partitioned Ticket Lock "PTL" (US20120240126-A1) and the MultiLane Concurrent Bag (US8689237). The latter is essentially a circular ring-buffer where the elements themselves are queues or concurrent collections. You can think of the PTLQueue as a partitioned ticket lock "PTL" augmented to pass values from lock to unlock via the slots. Alternatively, you could conceptualize of PTLQueue as a degenerate MultiLane bag where each slot or "lane" consists of a simple single-word MailBox instead of a general queue. Each lane in PTLQueue also has a private Turn field which acts like the Turn (Grant) variables found in PTL. Turn enforces strict FIFO ordering and restricts concurrency on the slot mailbox field to at most one simultaneous put() and take() operation. PTL uses a single "ticket" variable and per-slot Turn (grant) fields while MultiLane has distinct PutCursor and TakeCursor cursors and abstract per-slot sub-queues. Both PTL and MultiLane advance their cursor and ticket variables with atomic fetch-and-increment. PTLQueue borrows from both PTL and MultiLane and has distinct put and take cursors and per-slot Turn fields. Instead of a per-slot queues, PTLQueue uses a simple single-word MailBox field. PutCursor and TakeCursor act like a pair of ticket locks, conferring "put" and "take" access to a given slot. PutCursor, for instance, assigns an incoming put() request to a slot and serves as a PTL "Ticket" to acquire "put" permission to that slot's MailBox field. To better explain the operation of PTLQueue we deconstruct the operation of put() and take() as follows. Put() first increments PutCursor obtaining a new unique ticket. That ticket value also identifies a slot. Put() next waits for that slot's Turn field to match that ticket value. This is tantamount to using a PTL to acquire "put" permission on the slot's MailBox field. Finally, having obtained exclusive "put" permission on the slot, put() stores the message value into the slot's MailBox. Take() similarly advances TakeCursor, identifying a slot, and then acquires and secures "take" permission on a slot by waiting for Turn. Take() then waits for the slot's MailBox to become non-empty, extracts the message, and clears MailBox. Finally, take() advances the slot's Turn field, which releases both "put" and "take" access to the slot's MailBox. Note the asymmetry : put() acquires "put" access to the slot, but take() releases that lock. At any given time, for a given slot in a PTLQueue, at most one thread has "put" access and at most one thread has "take" access. This restricts concurrency from general MPMC to 1-vs-1. We have 2 ticket locks -- one for put() and one for take() -- each with its own "ticket" variable in the form of the corresponding cursor, but they share a single "Grant" egress variable in the form of the slot's Turn variable. Advancing the PutCursor, for instance, serves two purposes. First, we obtain a unique ticket which identifies a slot. Second, incrementing the cursor is the doorway protocol step to acquire the per-slot mutual exclusion "put" lock. The cursors and operations to increment those cursors serve double-duty : slot-selection and ticket assignment for locking the slot's MailBox field. At any given time a slot MailBox field can be in one of the following states: empty with no pending operations -- neutral state; empty with one or more waiting take() operations pending -- deficit; occupied with no pending operations; occupied with one or more waiting put() operations -- surplus; empty with a pending put() or pending put() and take() operations -- transitional; or occupied with a pending take() or pending put() and take() operations -- transitional. The partial put() and take() operators can be implemented with an atomic fetch-and-increment operation, which may confer a performance advantage over a CAS-based loop. In addition we have independent PutCursor and TakeCursor cursors. Critically, a put() operation modifies PutCursor but does not access the TakeCursor and a take() operation modifies the TakeCursor cursor but does not access the PutCursor. This acts to reduce coherence traffic relative to some other queue designs. It's worth noting that slow threads or obstruction in one slot (or "lane") does not impede or obstruct operations in other slots -- this gives us some degree of obstruction isolation. PTLQueue is not lock-free, however. The implementation above is expressed with polite busy-waiting (Pause) but it's trivial to implement per-slot parking and unparking to deschedule waiting threads. It's also easy to convert the queue to a more general deque by replacing the PutCursor and TakeCursor cursors with Left/Front and Right/Back cursors that can move either direction. Specifically, to push and pop from the "left" side of the deque we would decrement and increment the Left cursor, respectively, and to push and pop from the "right" side of the deque we would increment and decrement the Right cursor, respectively. We used a variation of PTLQueue for message passing in our recent OPODIS 2013 paper. ul { list-style:none; padding-left:0; padding:0; margin:0; margin-left:0; } ul#myTagID { padding: 0px; margin: 0px; list-style:none; margin-left:0;} -- -- There's quite a bit of related literature in this area. I'll call out a few relevant references: Wilson's NYU Courant Institute UltraComputer dissertation from 1988 is classic and the canonical starting point : Operating System Data Structures for Shared-Memory MIMD Machines with Fetch-and-Add. Regarding provenance and priority, I think PTLQueue or queues effectively equivalent to PTLQueue have been independently rediscovered a number of times. See CB-Queue and BNPBV, below, for instance. But Wilson's dissertation anticipates the basic idea and seems to predate all the others. Gottlieb et al : Basic Techniques for the Efficient Coordination of Very Large Numbers of Cooperating Sequential Processors Orozco et al : CB-Queue in Toward high-throughput algorithms on many-core architectures which appeared in TACO 2012. Meneghin et al : BNPVB family in Performance evaluation of inter-thread communication mechanisms on multicore/multithreaded architecture Dmitry Vyukov : bounded MPMC queue (highly recommended) Alex Otenko : US8607249 (highly related). John Mellor-Crummey : Concurrent queues: Practical fetch-and-phi algorithms. Technical Report 229, Department of Computer Science, University of Rochester Thomasson : FIFO Distributed Bakery Algorithm (very similar to PTLQueue). Scott and Scherer : Dual Data Structures I'll propose an optimization left as an exercise for the reader. Say we wanted to reduce memory usage by eliminating inter-slot padding. Such padding is usually "dark" memory and otherwise unused and wasted. But eliminating the padding leaves us at risk of increased false sharing. Furthermore lets say it was usually the case that the PutCursor and TakeCursor were numerically close to each other. (That's true in some use cases). We might still reduce false sharing by incrementing the cursors by some value other than 1 that is not trivially small and is coprime with the number of slots. Alternatively, we might increment the cursor by one and mask as usual, resulting in a logical index. We then use that logical index value to index into a permutation table, yielding an effective index for use in the slot array. The permutation table would be constructed so that nearby logical indices would map to more distant effective indices. (Open question: what should that permutation look like? Possibly some perversion of a Gray code or De Bruijn sequence might be suitable). As an aside, say we need to busy-wait for some condition as follows : "while C == 0 : Pause". Lets say that C is usually non-zero, so we typically don't wait. But when C happens to be 0 we'll have to spin for some period, possibly brief. We can arrange for the code to be more machine-friendly with respect to the branch predictors by transforming the loop into : "if C == 0 : for { Pause; if C != 0 : break; }". Critically, we want to restructure the loop so there's one branch that controls entry and another that controls loop exit. A concern is that your compiler or JIT might be clever enough to transform this back to "while C == 0 : Pause". You can sometimes avoid this by inserting a call to a some type of very cheap "opaque" method that the compiler can't elide or reorder. On Solaris, for instance, you could use :"if C == 0 : { gethrtime(); for { Pause; if C != 0 : break; }}". It's worth noting the obvious duality between locks and queues. If you have strict FIFO lock implementation with local spinning and succession by direct handoff such as MCS or CLH,then you can usually transform that lock into a queue. Hidden commentary and annotations - invisible : * And of course there's a well-known duality between queues and locks, but I'll leave that topic for another blog post. * Compare and contrast : PTLQ vs PTL and MultiLane * Equivalent : Turn; seq; sequence; pos; position; ticket * Put = Lock; Deposit Take = identify and reserve slot; wait; extract & clear; unlock * conceptualize : Distinct PutLock and TakeLock implemented as ticket lock or PTL Distinct arrival cursors but share per-slot "Turn" variable provides exclusive role-based access to slot's mailbox field put() acquires exclusive access to a slot for purposes of "deposit" assigns slot round-robin and then acquires deposit access rights/perms to that slot take() acquires exclusive access to slot for purposes of "withdrawal" assigns slot round-robin and then acquires withdrawal access rights/perms to that slot At any given time, only one thread can have withdrawal access to a slot at any given time, only one thread can have deposit access to a slot Permissible for T1 to have deposit access and T2 to simultaneously have withdrawal access * round-robin for the purposes of; role-based; access mode; access role mailslot; mailbox; allocate/assign/identify slot rights; permission; license; access permission; * PTL/Ticket hybrid Asymmetric usage ; owner oblivious lock-unlock pairing K-exclusion add Grant cursor pass message m from lock to unlock via Slots[] array Cursor performs 2 functions : + PTL ticket + Assigns request to slot in round-robin fashion Deconstruct protocol : explication put() : allocate slot in round-robin fashion acquire PTL for "put" access store message into slot associated with PTL index take() : Acquire PTL for "take" access // doorway step seq = fetchAdd (&Grant, 1) s = &Slots[seq & Mask] // waiting phase while s-Turn != seq : pause Extract : wait for s-mailbox to be full v = s-mailbox s-mailbox = null Release PTL for both "put" and "take" access s-Turn = seq + Mask + 1 * Slot round-robin assignment and lock "doorway" protocol leverage the same cursor and FetchAdd operation on that cursor FetchAdd (&Cursor,1) + round-robin slot assignment and dispersal + PTL/ticket lock "doorway" step waiting phase is via "Turn" field in slot * PTLQueue uses 2 cursors -- put and take. Acquire "put" access to slot via PTL-like lock Acquire "take" access to slot via PTL-like lock 2 locks : put and take -- at most one thread can access slot's mailbox Both locks use same "turn" field Like multilane : 2 cursors : put and take slot is simple 1-capacity mailbox instead of queue Borrow per-slot turn/grant from PTL Provides strict FIFO Lock slot : put-vs-put take-vs-take at most one put accesses slot at any one time at most one put accesses take at any one time reduction to 1-vs-1 instead of N-vs-M concurrency Per slot locks for put/take Release put/take by advancing turn * is instrumental in ... * P-V Semaphore vs lock vs K-exclusion * See also : FastQueues-excerpt.java dice-etc/queue-mpmc-bounded-blocking-circular-xadd/ * PTLQueue is the same as PTLQB - identical * Expedient return; ASAP; prompt; immediately * Lamport's Bakery algorithm : doorway step then waiting phase Threads arriving at doorway obtain a unique ticket number Threads enter in ticket order * In the terminology of Reed and Kanodia a ticket lock corresponds to the busy-wait implementation of a semaphore using an eventcount and a sequencer It can also be thought of as an optimization of Lamport's bakery lock was designed for fault-tolerance rather than performance Instead of spinning on the release counter, processors using a bakery lock repeatedly examine the tickets of their peers --

  Read the article

< Previous Page | 103 104 105 106 107 108 109 110 111 112 113 114  | Next Page >