0 Replies Latest reply: Feb 19, 2013 4:48 PM by 991202 RSS

    Unexpected Full GC: Why did we have a Full GC here?

    991202
      Hi,

      I have a scenario where a Full GC occurred. Here are the VM parameters.

      /usr/jdk/jdk1.6.0_24/bin/java -ms6144M -mx6144M -XX:MaxPermSize=256M -XX:+UseParNewGC -XX:SurvivorRatio=8 -XX:ParallelGCThreads=20 -Xloggc:logs/JVM_GC.log -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintTenuringDistribution -XX:+PrintHeapAtGC -XX:+PrintVMOptions

      Note: I am not using a CMS here. Parallel GC is used by default due to my system configs.

      Here is the corresponding log messages: I failed to understand what is the cause of this Full GC. There is no failures in GC log. Tenured is still have lot of space. This Full GC is not by RMI. PERM Gen remained same before and after GC.
      Can someone explain why a Full GC occurred here?
      {Heap before GC invocations=8427 (full 34):
      par new generation total 1887488K, used 1076526K [0x0000000670000000, 0x00000006f0000000, 0x00000006f0000000)
      eden space 1677824K, 60% used [0x0000000670000000, 0x00000006adf8a0e0, 0x00000006d6680000)
      from space 209664K, 29% used [0x00000006e3340000, 0x00000006e6f01a20, 0x00000006f0000000)
      to space 209664K, 0% used [0x00000006d6680000, 0x00000006d6680000, 0x00000006e3340000)
      tenured generation total 4194304K, used 2897518K [0x00000006f0000000, 0x00000007f0000000, 0x00000007f0000000)
      the space 4194304K, 69% used [0x00000006f0000000, 0x00000007a0d9b848, 0x00000007a0d9ba00, 0x00000007f0000000)
      compacting perm gen total 169280K, used 169279K [0x00000007f0000000, 0x00000007fa550000, 0x0000000800000000)
      the space 169280K, 99% used [0x00000007f0000000, 0x00000007fa54ffc8, 0x00000007fa550000, 0x00000007fa550000)
      No shared spaces configured.
      +2013-02-07T21:48:06.801+0000: 418726.755: [Full GC 418726.755: [Tenured: 2897518K->1136578K(4194304K), 2.6452830 secs] 3974044K->1136578K(6081792K), [Perm : 169279K->169279K(169280K)], 2.6458510 secs] [Times: user=2.64 sys=0.01, real=2.65 secs]+
      Heap after GC invocations=8428 (full 35):
      par new generation total 1887488K, used 0K [0x0000000670000000, 0x00000006f0000000, 0x00000006f0000000)
      eden space 1677824K, 0% used [0x0000000670000000, 0x0000000670000000, 0x00000006d6680000)
      from space 209664K, 0% used [0x00000006e3340000, 0x00000006e3340000, 0x00000006f0000000)
      to space 209664K, 0% used [0x00000006d6680000, 0x00000006d6680000, 0x00000006e3340000)
      tenured generation total 4194304K, used 1136578K [0x00000006f0000000, 0x00000007f0000000, 0x00000007f0000000)
      the space 4194304K, 27% used [0x00000006f0000000, 0x00000007355f08a8, 0x00000007355f0a00, 0x00000007f0000000)
      compacting perm gen total 169280K, used 169279K [0x00000007f0000000, 0x00000007fa550000, 0x0000000800000000)
      the space 169280K, 99% used [0x00000007f0000000, 0x00000007fa54ffc8, 0x00000007fa550000, 0x00000007fa550000)
      No shared spaces configured.
      }

      Thanks,
      Karthik