Heap Utilization on WP WCM - Websphere

This is a discussion on Heap Utilization on WP WCM - Websphere ; I'm trying to optimize the heap utilization of my WS Portal WCM application servers. I'm on 6.0.1.3. I have calculated the pClusters using -Dibm.dg.trc.print=st_verify and the proper value for kCluster as well. These JVMs does not specify the -Xminf or ...

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Thread: Heap Utilization on WP WCM

  1. Heap Utilization on WP WCM

    I'm trying to optimize the heap utilization of my WS Portal WCM application servers. I'm on 6.0.1.3.

    I have calculated the pClusters using -Dibm.dg.trc.print=st_verify and the proper value for kCluster as well.

    These JVMs does not specify the -Xminf or -Xmaxf, but still my free heap is constantly around 60%.

    I would be glad if anyone can point me to a resource which explains this scenario.









    GC(793): GC cycle started Mon Oct 20 09:46:26 2008






  2. Re: Heap Utilization on WP WCM

    Hello,
    The above verbosegc trace is normal. See [verbosegc output from an allocation failure|http://publib.boulder.ibm.com/infoce...l/id1150.html].

    An allocation failure does not mean that an error has occurred in the code; it is the name that is given to the event that triggers when it is not possible to allocate a large enough chunk from the heap.

    The JVM executed a garbage collection in order to resolve the allocation failure. It freed 63% of the heap and was able to complete the 528 byte allocation request afterwards.

    The *Garbage Collection and Memory Visualizer (GCMV)* in the IBM Support Assistant tool can help you analyze the verbosegc trace.

    Also, just FYI, the Java version 1.4.2 command line parameter pCluster size (-Xp) works only for Garbage Collector policy (-Xgcpolicy:subpool). Otherwise, it does not do anything.

    Thank you,
    David Yang
    WebSphere Portal support

    The postings on this site are my own and do not necessarily represent the positions, strategies, or opinions of IBM.

  3. Re: Heap Utilization on WP WCM

    Hi David,

    According to Java 1.4.2 Diagnostic Guide the -Xgcpolicy:subpool is recommended for multi processor environments (like 16 way systems). But my systems are 2 way systems (with SMT enabled, closely 4 way). Do you know any side effects if I use Garbage Collection Policy??

    Thanx,
    Kosala

  4. Re: Heap Utilization on WP WCM

    Hello,
    Based on the description of your physical system, -Xgcpolicy:subpool is not appropriate for you.

    If you have further questions about the subpool garbage collection policy, please try posting them on the [IBM Java Runtimes and SDKs|http://www.ibm.com/developerworks/fo...a?forumID=367] forum.

    Thank you,
    David Yang
    WebSphere Portal support

    The postings on this site are my own and do not necessarily represent the positions, strategies, or opinions of IBM.

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