Java Heap size

Discussions

Performance and scalability: Java Heap size

  1. Java Heap size (2 messages)

    Hi Everyone,

    I am new to Weblogic tuning and we are facing some problem regarding Heap size and frequent running for GC.

    In weblogic console,the max heap size that get consumed is only 40% of the total available value. The value for -Xms & -Xmx are set to 1024m. Its running on Solaris and we have enough RAM available. Once the Heap size reaches 40% of 1024MB the GC starts and heap size get reduced to around 10%. -XX:MinHeapFreeRatio & -XX:MaxHeapFreeRatio are set to default value and I think it is 40 and 70 resp. GC is running every 1-2 min.


    Why the heap size memory does not increase beyond 40%? Why GC starts once heap size reaches 40%? Is there any parameter needs to be set or missing?

    Thanks in advance!

    Kapil

    Threaded Messages (2)

  2. Try setting MaxPermSize[ Go to top ]

    You might try setting the MaxPermSize value to a higher value. Often, the reason for frequent collections is due not only to the regular heap from filling up, but also if the permanent area of the heap fills up. The permanent area is used to store the class files, but if this fills up (i.e if you have a lot of classes loaded into memory, but not a lot of instances of each class), then you will still see frequent collections.

    I realize this is a bit of a late response, but thought I'd go ahead and chime in.

    Clay

    J2EE 911
  3. Java Heap size[ Go to top ]

    Hi Everyone,I am new to Weblogic tuning and we are facing some problem regarding Heap size and frequent running for GC.In weblogic console,the max heap size that get consumed is only 40% of the total available value. The value for -Xms & -Xmx are set to 1024m. Its running on Solaris and we have enough RAM available. Once the Heap size reaches 40% of 1024MB the GC starts and heap size get reduced to around 10%. -XX:MinHeapFreeRatio & -XX:MaxHeapFreeRatio are set to default value and I think it is 40 and 70 resp. GC is running every 1-2 min.Why the heap size memory does not increase beyond 40%? Why GC starts once heap size reaches 40%? Is there any parameter needs to be set or missing? Thanks in advance!Kapil

    I think that should consider starting the JVM with -Xms set to merely 256 mb. It looks like you don't need 1024 mb, because the max used heap size never reaches the 40% of this amount of memory.


    Jose Ramon Huerga
    http://www.terra.es/personal/jrhuerga