AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  verboseGC action meanings          AppletTalk.com Forum Index -> ibm.software.java.linux View previous topic :: View next topic   Author Message Dave Pinkney Guest Posted: Mon Apr 26, 2004 6:08 pm    Post subject: verboseGC action meanings Hello, I am running the following IBM JDK and have a question regarding the GC actions: java version "1.4.1" Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1) Classic VM (build 1.4.1, J2RE 1.4.1 IBM build cxia321411-20030930 (JIT enabled: jitc)) According to the diagnostics guide for 1.4.1sr1 "Third Edition (October 2003)", action 7 corresponds to "This is not an action. It outputs a verbosegc message to say that the JVM is very low on heap space, or totally out of heap space." From looking at the -verbosegc output, it appears that this is reported as action 6: <AF[18759]: managing allocation failure, action=6 (96247720/268433920)> JVMDG217: Dump Handler is Processing a Signal - Please Wait. JVMDG315: JVM Requesting Heap dump file ..JVMDG318: Heap dump file written to /permabit/user/dpinkney/sandboxes/c/src/java/server/heapdump.20040425.1 80258.395.txt JVMDG303: JVM Requesting Java core file JVMDG304: Java core file written to /permabit/user/dpinkney/sandboxes/c/src/java/server/javacore.20040425.18 0304.395.txt JVMDG215: Dump Handler has Processed Outofmemory Signal -1. <AF[18759]: insufficient heap space to satisfy allocation request> What is the actual meaning of action 6? Thank you, Dave Pinkney -- dave Back to top Devaprasad Guest Posted: Thu May 06, 2004 10:16 am    Post subject: Re: verboseGC action meanings This option refers to resettable JVMs only. Resettable JVMs use 4 heaps. 1. System heap 2. Application class system heap 3. Main heap and 4. Transient heap. Transient is a real heap and contains short life time objects like non-sharaeable application classes, application objects and arrays, primordial objects/arrays allocated by applications. This is intended not to be GC'ed, but will be GC'ed if necessary. One can use the -Xinitth parameter to mention the initial Trnasient heap space size. Note that transient heap is a part of the total heap. In a resettable JVM, transient heap is cleared first. Quote: ---------------| | | Transient Heap | ---------------| | | Free space | | ---------------| | | | | Middleware heap | | | ---------------| The action 6 is invoked when there is no space in the heap and when the GC is going to free some space from the transient heap. In this verbose GC case, the heap space ran out of memory and transient heap could not also be cleared. This being the reason a heap dump and a javacore is dumped into the system. If you don't want the heap dump, you can export IBM_HEAPDUMP_OUTOFMEMORY="FALSE" environment variable. Hope that answers your question. Dave Pinkney wrote: Quote: Hello, I am running the following IBM JDK and have a question regarding the GC actions: java version "1.4.1" Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1) Classic VM (build 1.4.1, J2RE 1.4.1 IBM build cxia321411-20030930 (JIT enabled: jitc)) According to the diagnostics guide for 1.4.1sr1 "Third Edition (October 2003)", action 7 corresponds to "This is not an action. It outputs a verbosegc message to say that the JVM is very low on heap space, or totally out of heap space." From looking at the -verbosegc output, it appears that this is reported as action 6: AF[18759]: managing allocation failure, action=6 (96247720/268433920) JVMDG217: Dump Handler is Processing a Signal - Please Wait. JVMDG315: JVM Requesting Heap dump file .JVMDG318: Heap dump file written to /permabit/user/dpinkney/sandboxes/c/src/java/server/heapdump.20040425.1 80258.395.txt JVMDG303: JVM Requesting Java core file JVMDG304: Java core file written to /permabit/user/dpinkney/sandboxes/c/src/java/server/javacore.20040425.18 0304.395.txt JVMDG215: Dump Handler has Processed Outofmemory Signal -1. AF[18759]: insufficient heap space to satisfy allocation request What is the actual meaning of action 6? Thank you, Dave Pinkney -- dave Back to top Walter Harrier Guest Posted: Wed May 12, 2004 4:43 pm    Post subject: Re: verboseGC action meanings I'm currently trying to diagnose a problem where my server starts dumping out heap dumps at the rate of about 6 an hour and fills up the drive. The documentation for IBM_HEAPDUMP_OUTOFMEMORY implies that this defaults to false(it says to set it to true to enable). I'm going to set it to false anyway and hopefully will stop getting the heap dumps while I try to figure out the problem. However, do you know what the default value is? The platform is Linux and the JVM is cxia32131-20031021. Thanks, Walter Harrier "Devaprasad" <devaprasad (AT) in (DOT) ibm.com> wrote Quote: This option refers to resettable JVMs only. Resettable JVMs use 4 heaps. 1. System heap 2. Application class system heap 3. Main heap and 4. Transient heap. Transient is a real heap and contains short life time objects like non-sharaeable application classes, application objects and arrays, primordial objects/arrays allocated by applications. This is intended not to be GC'ed, but will be GC'ed if necessary. One can use the -Xinitth parameter to mention the initial Trnasient heap space size. Note that transient heap is a part of the total heap. In a resettable JVM, transient heap is cleared first. |---------------| | | | | Transient Heap | | |---------------| | | | | Free space | | | | |---------------| | | | | | | | | Middleware heap | | | | | | |---------------| The action 6 is invoked when there is no space in the heap and when the GC is going to free some space from the transient heap. In this verbose GC case, the heap space ran out of memory and transient heap could not also be cleared. This being the reason a heap dump and a javacore is dumped into the system. If you don't want the heap dump, you can export IBM_HEAPDUMP_OUTOFMEMORY="FALSE" environment variable. Hope that answers your question. Dave Pinkney wrote: Hello, I am running the following IBM JDK and have a question regarding the GC actions: java version "1.4.1" Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1) Classic VM (build 1.4.1, J2RE 1.4.1 IBM build cxia321411-20030930 (JIT enabled: jitc)) According to the diagnostics guide for 1.4.1sr1 "Third Edition (October 2003)", action 7 corresponds to "This is not an action. It outputs a verbosegc message to say that the JVM is very low on heap space, or totally out of heap space." From looking at the -verbosegc output, it appears that this is reported as action 6: AF[18759]: managing allocation failure, action=6 (96247720/268433920) JVMDG217: Dump Handler is Processing a Signal - Please Wait. JVMDG315: JVM Requesting Heap dump file .JVMDG318: Heap dump file written to /permabit/user/dpinkney/sandboxes/c/src/java/server/heapdump.20040425.1 80258.395.txt JVMDG303: JVM Requesting Java core file JVMDG304: Java core file written to /permabit/user/dpinkney/sandboxes/c/src/java/server/javacore.20040425.18 0304.395.txt JVMDG215: Dump Handler has Processed Outofmemory Signal -1. AF[18759]: insufficient heap space to satisfy allocation request What is the actual meaning of action 6? Thank you, Dave Pinkney -- dave Back to top Devaprasad Guest Posted: Mon Jun 28, 2004 6:35 am    Post subject: Re: verboseGC action meanings Sorry.. I couldn't access the news groups for a long time now. By default the heap dump is enabled on out of memory errors in later JVMs. This is to facilitate the heap dump analysis on out of memory errors. You need to tune the JVM so as to avoid these out of memory errors. Cheers, Dev Checkout the diagnostics guide at http://www.ibm.com/developerworks/java/jdk/diagnosis/ Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AppletTalk.com Forum Index -> ibm.software.java.linux All times are GMT Page 1 of 1   Jump to: Select a forum Java Newsgroups----------------Java DiscussionsWeb-based java games comp.lang.java 3D Graphics API's for Java Java: Support and criticism Java System Announcements comp.lang.java.api JavaBeans Java and CORBA Java and Databases comp.lang.java.developer Java GUI Toolkits Java Help comp.lang.java.javascript JVM, native methods and hardware comp.lang.java.misc Java Language Programming Security and Java comp.lang.java.setup Java Software Tools comp.lang.java.tech ibm.software.java.linux  Non-English Java Newsgroups----------------Java Language (German)Language Java (Français)Java (Italian)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.