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6 replies Latest Post - ‏2012-10-20T18:50:30Z by ChrisBailey
WiseMind
WiseMind
6 Posts
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Pinned topic increse heap size IBM JVM on AIX

‏2012-10-09T09:41:13Z |
Hi,

How to increase JVM heap size on AIX machine ? and how to check existing and updated JVM heap size ?

Is there any way to restart JDK / JVM on AIX? how ?

Thanks
Updated on 2012-10-20T18:50:30Z at 2012-10-20T18:50:30Z by ChrisBailey
  • SystemAdmin
    SystemAdmin
    2736 Posts
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    Re: increse heap size IBM JVM on AIX

    ‏2012-10-09T16:53:47Z  in response to WiseMind
    The -Xmx switch/option controls the "maximum" heap size on the IBM JVM as well as Oracle JVM .
    You need to tune this to the appropriate size on your JVM instance.

    The way to restart your Java is by gracefully shutting it down and starting it again - unless there's a different way you are using the IBM JDK like running underneath WAS or Lotus Domino or DB2 etc

    If you have WAS running on IBM Java, then the WAS Admin Console's "JVM Generic Arguments" is where you can put the Xmx value and RESTART the server - which means the new option is picked up.

    WAS has scripts to start and stop the server which should serve the purpose.

    If there's something I have mis-understood please let us know so that we can answer the query to the utmost accuracy.
    • WiseMind
      WiseMind
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      Re: increse heap size IBM JVM on AIX

      ‏2012-10-10T08:13:53Z  in response to SystemAdmin
      Hi,

      I am using Oracle application server above IBM JDK. Well IBM JDK got crashed due to some application having more memory consumption. So I need to increase heap size of IBM JDK and also need to see current heap size alocated from JVM.

      Can you please tell me the JVM commands ? like

      java -Xmx 1024m

      It is fine to increase heap size of JVM ? but when I entered command

      java -verbose:sizes

      It has no effect and showing the previous JVM heap size. Am I missing something ?

      help me. Thanks
      • SystemAdmin
        SystemAdmin
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        Re: increse heap size IBM JVM on AIX

        ‏2012-10-11T03:24:31Z  in response to WiseMind
        The right way to set the heap size is as follows - notice that there's no space after Xmx and the heap size
        java -Xmx1024M <application>

        If you need to know if you option has taken effect , then it has to be done this way
        java -Xmx1024m -verbose:sizes <application>
        • WiseMind
          WiseMind
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          Re: increse heap size IBM JVM on AIX

          ‏2012-10-12T06:17:11Z  in response to SystemAdmin
          Thank you so much for your reply.

          Actually I want to increase the heap size of JVM only not for application.

          How can I increase the size of JVM only ?

          I am giving the following command but i don't show any effect.
          java -Xmx1024m -verbose:sizes

          Any other way around ??

          Thanks
        • WiseMind
          WiseMind
          6 Posts
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          Re: increse heap size IBM JVM on AIX

          ‏2012-10-15T10:33:49Z  in response to SystemAdmin
          Any one has worked on it ??

          Thanks
          • ChrisBailey
            ChrisBailey
            190 Posts
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            Re: increse heap size IBM JVM on AIX

            ‏2012-10-20T18:50:30Z  in response to WiseMind
            Are you looking to control the "native" (non-Java heap) memory usage of the Java application?

            If so, you really need to understand how a process uses memory on AIX. There's a developerWorks article by Andrew Hall that covers this in detail:
            http://www.ibm.com/developerworks/aix/library/j-nativememory-aix/index.html