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  • Is the Java classpath final after JVM startup?

    - by Jens
    Hi, I have read a lot about the Java class loading process lately. Often I came across texts that claimed that it is not possible to add classes to the classpath during runtime and load them without class loader hackery (URLClassLoaders etc.) As far as I know classes are loaded dynamically. That means their bytecode representation is only loaded and transformed to a java.lang.Class object when needed. So shouldn't it be possible to add a JAR or *.class file to the classpath after the JVM started and load those classes, provided they haven't been loaded yet? (To be clear: In this case the classpath is simple folder on the filesystem. "Adding a JAR or *.class file" simply means dropping them in this folder.) And if not, does that mean that the classpath is searched on JVM startup and all fully qualified names of the found classes are cached in an internal "list"? It would be nice of you if you could point me to some sources in your answers. Preferably the offical SUN documentation: Sun JVM Spec. I have read the spec but could not find anything about the classpath and if it's finalized on JVM startup. P.s. This is a theoretical question. I just want to know if it is possible. There is nothing practical I want to achieve. There is just my thirst for knowledge :)

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  • Converting ANTLR AST to Java bytecode using ASM

    - by Nick
    I am currently trying to write my own compiler, targeting the JVM. I have completed the parsing step using Java classes generated by ANTLR, and have an AST of the source code to work from (An ANTLR "CommonTree", specifically). I am using ASM to simplify the generating of the bytecode. Could anyone give a broad overview of how to convert this AST to bytecode? My current strategy is to explore down the tree, generating different code depending on the current node (using "Tree.getType()"). The problem is that I can only recognise tokens from my lexer this way, rather than more complex patterns from the parser. Is there something I am missing, or am I simply approaching this wrong? Thanks in advance :)

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  • First impressions of Scala

    - by Scott Weinstein
    I have an idea that it may be possible to predict build success/failure based on commit data. Why Scala? It’s a JVM language, has lots of powerful type features, and it has a linear algebra library which I’ll need later. Project definition and build Neither maven or the scala build tool (sbt) are completely satisfactory. This maven **archetype** (what .Net folks would call a VS project template) mvn archetype:generate `-DarchetypeGroupId=org.scala-tools.archetypes `-DarchetypeArtifactId=scala-archetype-simple `-DremoteRepositories=http://scala-tools.org/repo-releases `-DgroupId=org.SW -DartifactId=BuildBreakPredictor gets you started right away with “hello world” code, unit tests demonstrating a number of different testing approaches, and even a ready made `.gitignore` file - nice! But the Scala version is behind at v2.8, and more seriously, compiling and testing was painfully slow. So much that a rapid edit – test – edit cycle was not practical. So Lab49 colleague Steve Levine tells me that I can either adjust my pom to use fsc – the fast scala compiler, or use sbt. Sbt has some nice features It’s fast – it uses fsc by default It has a continuous mode, so  `> ~test` will compile and run your unit test each time you save a file It’s can consume (and produce) Maven 2 dependencies the build definition file can be much shorter than the equivalent pom (about 1/5 the size, as repos and dependencies can be declared on a single line) And some real limitations Limited support for 3rd party integration – for instance out of the box, TeamCity doesn’t speak sbt, nor does IntelliJ IDEA Steeper learning curve for build steps outside the default Side note: If a language has a fast compiler, why keep the slow compiler around? Even worse, why make it the default? I choose sbt, for the faster development speed it offers. Syntax Scala APIs really like to use punctuation – sometimes this works well, as in the following map1 |+| map2 The `|+|` defines a merge operator which does addition on the `values` of the maps. It’s less useful here: http(baseUrl / url >- parseJson[BuildStatus] sure you can probably guess what `>-` does from the context, but how about `>~` or `>+`? Language features I’m still learning, so not much to say just yet. However case classes are quite usefull, implicits scare me, and type constructors have lots of power. Community A number of projects, such as https://github.com/scalala and https://github.com/scalaz/scalaz are split between github and google code – github for the src, and google code for the docs. Not sure I understand the motivation here.

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  • Experience of moving to 64 bit JVM

    - by Fazal
    Our company is planning to move to 64 bit JVM in order to get away from 2 GB maximum heap size limit. Google gave me very mixed results about 64 bit JVM performance. Has anyone tried moving to 64 bit java and share your experience

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  • outofmemory error for Windows 2008 server(64 bit) and JBOSS 5.0.1,64bit jvm

    - by Amar dhole
    Hi All, I have ear deployed in jboss 5.0.1, on windows 2008 which is 64 bit machine and we are using 64jvm, with this combination our VFS temp size increases a lot eventually all our physical hard drive space is used by replicating files. but if we change our JVm from 64 to 32 every thing looks ok. does any one one what is reason ?and possible solution as we want ot use 64bit jvm. Thanks

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  • Coldfusion multiserver instance hangs

    - by David Sedeño
    I have a coldfusion 8 multiserver setup with IIS in Windows 2008 Standard SP2 and when one instance "hangs" (I can't connect to the instance from fusion reactor) the web server throws a "503 service unavailable". The remains instance seems to works ok in fusion reactor but the website have only the 503. I have to restart jvm processes and IIS to get the website work again. The jvm processes have the option -Xmx2048m and the instanaces have 2.5Gb allocated. Maybe the jvm process reach the 2Gb limit and stop working? Can be a problem between IIS and CF instances? I'm new to CF debugging process, how can I find why the instance hangs? Thanks

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  • How to differentiate between Programmer and JVM Exceptions

    - by Haxed
    As the title suggests, how can I tell a JVM thrown exception from a Programmatically(does this mean, thrown by a programmer or the program) thrown exception ? JVM Exceptions 1) ArrayIndexOutOfBoundsException 2) ClassCastException 3) NullPointerException Programmatically thrown 1) NumberFormatException 2) AssertionError Many Thanks

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  • How to deferentiate between Programmer and JVM Exceptions

    - by Haxed
    As the title suggests, how can I tell a JVM thrown exception from a Programmatically(does this mean, thrown by a programmer or the program) thrown exception ? JVM Exceptions 1) ArrayIndexOutOfBoundsException 2) ClassCastException 3) NullPointerException Programmatically thrown 1) NumberFormatException 2) AssertionError Many Thanks

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  • Obtaining memory available to JVM at runtime

    - by Bo Tian
    I'm trying to sort a bunch of data such that that the size of data input to the program can be larger than the memory available to the JVM, and handling that requires external sort which is much slower than Quicksort. Is there any way of obtaining memory available to the JVM at runtime such that I could use in place sorting as much as possible, and only switch to Mergesort when data input is too large?

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  • Why are Full GCs not running on my gcInterval I set?

    - by Brad Wood
    ColdFusion 10 Update 10 Windows Server 2008 R2 Java 1.7.0_21 I am trying to figure Full GCs to run every 10 minutes. I have used the gcInterval JVM arg in the past on earlier versions of ColdFusion with success, but I have confirmed with verbose GC logs that Full GCs are still happening on the hour (Unless the Old Gen gets so full that it forces a full collection). Here are the full JVM args from ColdFusion10\cfusion\bin\jvm.config (line breaks added for readability) Is there something else I need to be doing to get this working on ColdFusion 10? java.args= -server -Xms4072m -Xmx4072m -XX:PermSize=512m -XX:MaxPermSize=512m -Dsun.rmi.dgc.client.gcInterval=600000 -Dsun.rmi.dgc.server.gcInterval=600000 -XX:+UseParallelGC -XX:+UseParallelOldGC -Xloggc:gc.log -verbose:gc -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintGCTimeStamps -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=5 -XX:GCLogFileSize=1024K -Xbatch -Dcoldfusion.home={application.home} -Dcoldfusion.rootDir={application.home} -Dcoldfusion.libPath={application.home}/lib -Dorg.apache.coyote.USE_CUSTOM_STATUS_MSG_IN_HEADER=true -Dcoldfusion.jsafe.defaultalgo=FIPS186Random -Dcoldfusion.classPath={application.home}/lib/updates,{application.home}/lib,{application.home}/lib/axis2,{application.home}/gateway/lib/,{application.home}/wwwroot/WEB-INF/flex/jars,{application.home}/wwwroot/WEB-INF/cfform/jars

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  • 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).

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  • JVM disappeared on Mac OS X Snow Leopard 10.6.8

    - by weisjohn
    I'm working in Eclipse one night, (also using Android's DDMS from the commandline). The next morning, I open the lid... attempt to run Eclipse and get an error. me$ sudo /Applications/eclipse/eclipse JavaVM: requested Java version ((null)) not available. Using Java at "" instead. JavaVM: Failed to load JVM: /bundle/Libraries/libserver.dylib So I then attempt to find out where my JDKs are pointed: me$ ls -la /System/Library/Frameworks/JavaVM.framework/Versions/ total 64 drwxr-xr-x 12 root wheel 408 Nov 16 10:44 . drwxr-xr-x 12 root wheel 408 Sep 7 09:39 .. lrwxr-xr-x 1 root wheel 5 Sep 7 17:07 1.3 -> 1.3.1 drwxr-xr-x 3 root wheel 102 Dec 2 2009 1.3.1 lrwxr-xr-x 1 root wheel 10 Sep 7 17:07 1.4 -> CurrentJDK lrwxr-xr-x 1 root wheel 10 Sep 7 17:07 1.4.2 -> CurrentJDK lrwxr-xr-x 1 root wheel 10 Sep 7 17:07 1.5 -> CurrentJDK lrwxr-xr-x 1 root wheel 10 Sep 7 17:07 1.5.0 -> CurrentJDK lrwxr-xr-x 1 root wheel 10 Sep 7 17:07 1.6 -> CurrentJDK drwxr-xr-x 9 root wheel 306 Nov 16 10:44 A lrwxr-xr-x 1 root wheel 1 Sep 7 17:07 Current -> A lrwxr-xr-x 1 root wheel 59 Sep 7 17:07 CurrentJDK -> /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents Everything looks normal so far... me$ ls -la /System/Library/Java/JavaVirtualMachines/ total 0 drwxr-xr-x 2 root wheel 68 Nov 16 10:44 . drwxr-xr-x 5 root wheel 170 Nov 16 10:44 .. Apparently, my virtual machines have been deleted or moved? I'll probably be able to just re-install Java, but does anyone have any insight into why this may have happened or how to prevent in the future?

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  • Orphan IBM JVM process

    - by Nicholas Key
    Hi people, I have this issue about orphan IBM JVM process being created in the process tree: For example: C:\Program Files\IBM\WebSphere\AppServer\bin>wsadmin -lang jython -f "C:\Hello.py" Hello.py has the simple implementation: import time i = 0 while (1): i = i + 1 print "Hello World " + str(i) time.sleep(3.0) My machine has such JVM information: C:\Program Files\WebSphere\java\bin>java -verbose:sizes -version -Xmca32K RAM class segment increment -Xmco128K ROM class segment increment -Xmns0K initial new space size -Xmnx0K maximum new space size -Xms4M initial memory size -Xmos4M initial old space size -Xmox1624995K maximum old space size -Xmx1624995K memory maximum -Xmr16K remembered set size -Xlp4K large page size available large page sizes: 4K 4M -Xmso256K operating system thread stack size -Xiss2K java thread stack initial size -Xssi16K java thread stack increment -Xss256K java thread stack maximum size java version "1.6.0" Java(TM) SE Runtime Environment (build pwi3260sr6ifix-20091015_01(SR6+152211+155930+156106)) IBM J9 VM (build 2.4, JRE 1.6.0 IBM J9 2.4 Windows Server 2003 x86-32 jvmwi3260sr6-20091001_43491 (JIT enabled, AOT enabled) J9VM - 20091001_043491 JIT - r9_20090902_1330ifx1 GC - 20090817_AA) JCL - 20091006_01 While the program is running, I tried to kill it and subsequently I found an orphan IBM JVM process in the process tree. Is there a way to fix this issue? Why is there an orphan process in the first place? Is there something wrong with my code? I really don't believe that my simplistic code is wrongly implemented. Any suggestions?

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  • Container Options in AWS Elastic Beanstalk

    - by Sangram Anand
    We have deployed a java webapplication in Elastic Beanstalk with the minimum instance count 1 and max instance count 2 for Autoscaling. The custom AMI we are using is c1.medium with Sun JDK 6. The environment status changed to yellow and then red. After checking into the log file from the snapshot logs we found a exception - Caused by: java.lang.OutOfMemoryError: Java heap space. Assuming this could be one of the possible reason for the Environment failure. The settings that we have configured in the Environment Container option are Initial JVM Heap Size (MB) - 256M Maximum JVM Heap Size (MB) - 512m The maximum heap size the java virtual machine will ever consume, specified on the JVM launch command line using -Xmx. Maximum JVM Permanent Generation Size (MB) - 512m Should i increase the Heap size from 512m to more or is it fine.

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  • My JVM crahes when i run my program.

    - by rgksugan
    I have written a program to process packets. The program runs well if its run alone but when i integrate it to my main project the jvm crashes and shows the below result. What is the problem? # # An unexpected error has been detected by HotSpot Virtual Machine: # # EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x6d7dcf6e, pid=4328, tid=4068 # # Java VM: Java HotSpot(TM) Client VM (1.5.0_16-b02 mixed mode, sharing) # Problematic frame: # V [jvm.dll+0x9cf6e] # # An error report file with more information is saved as hs_err_pid4328.log # # If you would like to submit a bug report, please visit: # http://java.sun.com/webapps/bugreport/crash.jsp #

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  • Why is memory management so visible in Java VM?

    - by Emil
    I'm playing around with writing some simple Spring-based web apps and deploying them to Tomcat. Almost immediately, I run into the need to customize the Tomcat's JVM settings with -XX:MaxPermSize (and -Xmx and -Xms); without this, the server easily runs out of PermGen space. Why is this such an issue for Java VMs compared to other garbage collected languages? Comparing counts of "tune X memory usage" for X in Java, Ruby, Perl and Python, shows that Java has easily an order of magnitude more hits in Google than the other languages combined. I'd also be interested in references to technical papers/blog-posts/etc explaining design choices behind JVM GC implementations, across different JVMs or compared to other interpreted language VMs (e.g. comparing Sun or IBM JVM to Parrot). Are there technical reasons why JVM users still have to deal with non-auto-tuning heap/permgen sizes?

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  • tomcat isolate webapps

    - by cometta
    multiple webapp running on same tomcat using same jvm. sometime, one webapp that have memory leak will cause entire jvm to crash and affect other webapps. any recommendation how to isolated that without need to use multiple jvm and tomcat

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  • ????????! ?????????????????JRockit Flight Recorder????|WebLogic Channel|??????

    - by ???02
    ???????????????????????????????????????WebLogic Server????????·??????????????????????????????????????????????WebLogic Server????????????????????????????????????????????????????????????????????????JRockit Flight Recorder???WebLogic Server????????????????????????????????????????????????????????????????????????????????????????(???)?????????????????――????????JRockit Flight Recorder ???????????·?????????????????????????????????????????????????????????????????????????????????? ????Java?????(JVM:Java Virtual Machine)??????????????????????????????????·??????????????????·?????????????????????????????????·???·????????????????????????????????????????????·?????JVM????????????????????????????????????????????????????????????????????????????????????????????? ???JVM?????????????·??????(Out of Memory Error)????????????????·???????????·??????(GC)?????????????????????????????????????????????????????????JVM?????????GC???????????????????????????????????????????????? ???????????????????2010?7?????????WebLogic Server Enterprise Edition 11g R1 Patch Set 2???????????????????JRockit Flight Recorder????????????????????????????????????????????????????????????????????????????????????????????????????JRockit Flight Recorder????????OS?????????·?????CPU??????????????????????JVM?????????JVM?????????·????????????·??????????????????·????????JVM?CPU????????·?????????·????JIT?????????????????Java????????·???????/???????????????/????????????WebLogic Server????????????EJB?JDBC?Web?????JTA?????????????????????????????? ??WebLogic Server??????????????????????????JRockit Runtime Analyzer??????????Runtime Analyzer?????????????????????????????????????????WebLogic Server?????????????????????????????????JRockit Flight Recorder?????????????????????????????????????????????? JRockit Flight Recorder???????????????????????????????????????????????????????? ???Java EE???????????????????????????????????????????????????JVM????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ???????JRockit Flight Recorder????JVM(JRockit)?????????????????????????????????????????????????????????????3%?????????????????????????????????????????????????????????????????????????? ????????JRockit Flight Recorder?????????????????????????????????????????????????????????????????????????JRockit Flight Recorder????? JRockit Flight Recorder????????????????????(????????????????????????)??????????????????????????(???????·????)??????????????? ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ???????JRockit Flight Recorder??????????????????????????????????????????·?????????????????????????????????????(?????GUI????Oracle JRockit Mission Control????)????????·??????????????????????????????JRockit Flight Recorder????????????????????? ??????????????????????JRockit Flight Recorder?WebLogic Server Enterprise Edition???????????WebLogic Server?????????????????????????????????????????????????????????????????????????????????????????????????? ??????????JRockit Flight Recorder????????????????????????????????????? ????????JRockit Flight Recorder??????????????????????????????????????????·?????????????????JRockit Mission Control??????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????????????????????????????????? ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ??????????????1????????????????????????????????????Thread Parked????????????????????????????????????????????Thread Parked????????????????????????????? ???JRockit Flight Recorder?JDBC??????????????????SQL?????????????????????????????????? ??????·???????????????????????????JRockit Flight Recorder?????????1???????????SLA?????? JRockit Flight Recorder????????????????????? ???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ????JRockit Flight Recorder???????????????????????????????????SLA(Service Level Agreement)?????????????????????????????????????????????????????????????????????????????????????????? ????????????JRockit Flight Recorder???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????JRockit Flight Recorder????????????1???JRockit Flight Recorder????????????????? ????????JRockit Flight Recorder?????????????????????????????????????????????????? ???JRockit Flight Recorder??????????????????1??????! ?????????????????????????????????3????????????????????????????6??????????????????13???????????????????????????????????????????????????????20???????????????????????35???????????????38?????????????????????????? ???????JRockit Flight Recorder???????????????????????????1??????! ??????????????????JRockit Flight Recorder??????????????????????3???????????????????18???????????????21?????????????????????????? ??????????????JRockit Flight Recorder????????????????????????????????????????JRockit Flight Recorder???????????????????????????????????????????????????JRockit Flight Recorder???????????? ??????????????????·???????????????????????JRockit Flight Recorder???????????????????????????? ???????????????????????????????――??????????????????? ???????????JRockit Flight Recorder??????2????1?????????????????????????????????????????????????????????? ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????JRockit Flight Recorder???????????????????????????????????????????????????????????????????SIer???????――???????/???????????????? JRockit Flight Recorder????????????????????IT?????????SIer????????????? ??????????????????????????SIer?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????(???????)?????????????????????????????????????????????????????????????????????????? ???JRockit Flight Recorder??????????????????????????????????????????????????????????????????????????????????????????/????????????????????????????????????????*   *   * ???????WebLogic Server Enterprise Edition???????????????????JRockit Flight Recorder????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????WebLogic Server?????????????JVM Oracle JRockit??? ???? ···???JVM?Oracle JRockit??????????????????????????JRockit Flight Recorder????????????????? ?????45???????????????????????????????????? ?WMV?? ?MP4??

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  • on coding style

    - by user12607414
    I vastly prefer coding to discussing coding style, just as I would prefer to write poetry instead of talking about how it should be written. Sometimes the topic cannot be put off, either because some individual coder is messing up a shared code base and needs to be corrected, or (worse) because some officious soul has decided, "what we really need around here are some strongly enforced style rules!" Neither is the case at the moment, and yet I will venture a post on the subject. The following are not rules, but suggested etiquette. The idea is to allow a coherent style of coding to flourish safely and sanely, as a humane, inductive, social process. Maxim M1: Observe, respect, and imitate the largest-scale precedents available. (Preserve styles of whitespace, capitalization, punctuation, abbreviation, name choice, code block size, factorization, type of comments, class organization, file naming, etc., etc., etc.) Maxim M2: Don't add weight to small-scale variations. (Realize that Maxim M1 has been broken many times, but don't take that as license to create further irregularities.) Maxim M3: Listen to and rely on your reviewers to help you perceive your own coding quirks. (When you review, help the coder do this.) Maxim M4: When you touch some code, try to leave it more readable than you found it. (When you review such changes, thank the coder for the cleanup. When you plan changes, plan for cleanups.) On the Hotspot project, which is almost 1.5 decades old, we have often practiced and benefited from such etiquette. The process is, and should be, inductive, not prescriptive. An ounce of neighborliness is better than a pound of police-work. Reality check: If you actually look at (or live in) the Hotspot code base, you will find we have accumulated many annoying irregularities in our source base. I suppose this is the normal condition of a lived-in space. Unless you want to spend all your time polishing and tidying, you can't live without some smudge and clutter, can you? Final digression: Grammars and dictionaries and other prescriptive rule books are sometimes useful, but we humans learn and maintain our language by example not grammar. The same applies to style rules. Actually, I think the process of maintaining a clean and pleasant working code base is an instance of a community maintaining its common linguistic identity. BTW, I've been reading and listening to John McWhorter lately with great pleasure. (If you end with a digression, is it a tail-digression?)

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  • ATG Live Webcast March 29: Diagnosing E-Business Suite JVM and Forms Performance Issues (Performance Series Part 4 of 4)

    - by BillSawyer
    The next webcast in our popular EBS series on performance management is going to be a showstopper.  Dave Suri, Project Lead, Applications Performance and Gustavo Jimenez, Senior Development Manager will discuss some of the steps involved in triaging and diagnosing E-Business Suite systems related to JVM and Forms components. Please join us for our next ATG Live Webcast on Mar. 29, 2012: Triage and Diagnostics for E-Business Suite JVM and Forms The topics covered in this webcast will be: Overall Menu/Sections Architecture Patches/Certified browsers/jdk versions JVM Tuning JVM Tools (jstat,eclipse mat, ibm tda) Forms Tools (strace/FRD) Java Concurrent Program options location Case studies Case Studies JVM Thread dump case for Oracle Advanced Product Catalog Forms FRD trace relating to Saving an SR Java Concurrent Program for BT Date:               Thursday, March 29, 2012Time:              8:00 AM - 9:00 AM Pacific Standard TimePresenters:  Dave Suri, Project Lead, Applications Performance                        Gustavo Jimenez, Senior Development ManagerWebcast Registration Link (Preregistration is optional but encouraged)To hear the audio feed:   Domestic Participant Dial-In Number:            877-697-8128    International Participant Dial-In Number:      706-634-9568    Additional International Dial-In Numbers Link:    Dial-In Passcode:                                              99342To see the presentation:    The Direct Access Web Conference details are:    Website URL: https://ouweb.webex.com    Meeting Number:  597073984 If you miss the webcast, or you have missed any webcast, don't worry -- we'll post links to the recording as soon as it's available from Oracle University.  You can monitor this blog for pointers to the replay. And, you can find our archive of our past webcasts and training here.If you have any questions or comments, feel free to email Bill Sawyer (Senior Manager, Applications Technology Curriculum) at BilldotSawyer-AT-Oracle-DOT-com. 

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  • How can Java be improved so that it no longer needs to perform type erasure? [closed]

    - by user63904
    The official Java tutorial on generics explains type erasure and why it was added to the compiler: When a generic type is instantiated, the compiler translates those types by a technique called type erasure — a process where the compiler removes all information related to type parameters and type arguments within a class or method. Type erasure enables Java applications that use generics to maintain binary compatibility with Java libraries and applications that were created before generics. This most likely was a pragmatic approach, or perhaps the least painful one. However, now that generics is widely supported across the industry, what can be done in order for us to not need type erasure? Is it feasible with out needing to break backwards compatibility, or if it is feasible, is it practical? Has the last the last statement in the quote above become self referential? That is: "type erasure enables Java applications that use generics to maintain binary compatibility with Java libraries and applications that were created with Java versions that perform type erasure."

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