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  1. JDK
  2. JDK-6493335

Mismatch between -Xm[sx] and verbose:gc output

    Details

    • Type: Bug
    • Status: Closed
    • Priority: P3
    • Resolution: Duplicate
    • Affects Version/s: 6
    • Fix Version/s: None
    • Component/s: hotspot
    • Labels:
    • Subcomponent:
      gc
    • CPU:
      generic
    • OS:
      generic

      Description

      As with 6493287, we're playing with the leaky program

      ------------------------------------------
      import java.util.concurrent.*;

      public class Bug3 {
          private static int intArg(String[] args, int i, int defaultValue) {
      return args.length > i ? Integer.parseInt(args[i]) : defaultValue;
          }

          public static void main(String[] args) {
      final BlockingQueue<Object> q = new LinkedBlockingQueue<Object>();
      final int threads = intArg(args, 0, 10);
      final int millis = intArg(args, 1, 100);

      for (int i = 0; i < threads; i++)
                  new Thread() { public void run() {
      while (true) {
      try { q.poll(millis, TimeUnit.MILLISECONDS); }
      catch (Throwable t) { throw new Error(t); }}}}.start();
          }
      }
      ------------------------------------------

      When specifying command line flags
      -Xms3m -Xmx3m
      I expect that the total heap size reported by -verbose:gc
      (that is, the number in parentheses)
      - will be about 3m
      - will be constant.

      Instead, I find that the reported total heap size sometimes grows, and
      is often much larger than 3m (6m-8m).

      Here's a run on linux-i586:

       $ jver 6 jr -verbose:gc -Xmx3m -Xms3m -XX:+UseSerialGC -server Bug3 10 100
      ==> javac -source 1.6 -Xlint:all Bug3.java
      ==> java -verbose:gc -Xmx3m -Xms3m -XX:+UseSerialGC -server -esa -ea Bug3 10 100
      [GC 896K->626K(3008K), 0.0155790 secs]
      [GC 1522K->1481K(3008K), 0.0197380 secs]
      [GC 2377K->2363K(3264K), 0.0158610 secs]
      [Full GC 2363K->2363K(3264K), 0.0720340 secs]
      [GC 3200K->3173K(4800K), 0.0368410 secs]
      [GC 4069K->4064K(5056K), 0.0149100 secs]
      [Full GC 4064K->4064K(5056K), 0.1115110 secs]
      [GC 4960K->4939K(6080K), 0.0142320 secs]
      [Full GC 5835K->5816K(6080K), 0.1493120 secs]
      [Full GC 6016K->5996K(6080K), 0.1833290 secs]
      [Full GC 6079K->6077K(6080K), 0.1464510 secs]
      [Full GC 6079K->6077K(6080K), 0.1460160 secs]

      Here's a run on solaris-sparc:

       $ jver 6 jr -verbose:gc -Xmx3m -Xms3m -XX:+UseParallelGC -client Bug3 10 100
      ==> javac -source 1.6 -Xlint:all Bug3.java
      ==> java -verbose:gc -Xmx3m -Xms3m -XX:+UseParallelGC -client -esa -ea Bug3 10 100
      [GC 1664K->1396K(6016K), 0.0308614 secs]
      [GC 3060K->3000K(6016K), 0.0459820 secs]
      [Full GC 3000K->2999K(7936K), 0.0641902 secs]
      [GC 4663K->4551K(7936K), 0.0819884 secs]
      [GC 6215K->6143K(7936K), 0.0414826 secs]
      [Full GC 6143K->6143K(7936K), 0.1156834 secs]
      [Full GC 7679K->7677K(7936K), 0.1436284 secs]
      [Full GC 7679K->7527K(7936K), 0.1652214 secs]

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              • Assignee:
                jwilhelm Jesper Wilhelmsson
                Reporter:
                martin Martin Buchholz
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                  Updated:
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