Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-6520834

(thread) Thread objects are not garbage collected

    XMLWordPrintable

    Details

    • Type: Bug
    • Status: Closed
    • Priority: P4
    • Resolution: Not an Issue
    • Affects Version/s: 6
    • Fix Version/s: None
    • Component/s: core-libs
    • Labels:
    • Subcomponent:
    • CPU:
      x86
    • OS:
      windows_xp

      Description

      FULL PRODUCT VERSION :
      C:\>java -version
      java version "1.6.0"
      Java(TM) SE Runtime Environment (build 1.6.0-b105)
      Java HotSpot(TM) Client VM (build 1.6.0-b105, mixed mode, sharing)

      ADDITIONAL OS VERSION INFORMATION :
      C:\>ver
      Microsoft Windows XP [Version 5.1.2600]

      A DESCRIPTION OF THE PROBLEM :
      After a thread stops, the Thread object never gets garbage collected.

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      1) Profile the attached source code in NetBeans 5.5.
      2) Select Analyze Memory Usage
      3) Select Record both Object Creation and Garbage Collection
      4) Select Track Every 1 Object Allocations
      5) Let the program run until you see some threads stopping
      6) Invoke the gabage collector
      7) Take a snapshot
      8) Repeat 5 to 7 a few times

      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      In the Memory snap shot I would expect to see that there are less Live "Threads" objects than Allocated "Threads" objects.
      ACTUAL -
      There is always the same number of Live "Threads" objects as Allocated "Threads" objects.

      This is clearly a memory leak defect.

      REPRODUCIBILITY :
      This bug can be reproduced always.

      ---------- BEGIN SOURCE ----------
      public class Threads extends Thread
      {
          public Threads()
          {
          }

          public void run()
          {
              System.out.println(getName() + " - starting");
              try
              {
                  sleep((int) (Math.random() * 100000));
              }
              catch (InterruptedException e)
              {
              }
              System.out.println(getName() + " - stopping");
          }

          public static void main(String [] arguments)
          {
              for (int i = 0; i < 100; i++)
              {
                  Threads threads = new Threads();
                  threads.start();
                  try
                  {
                      Thread.sleep(2000);
                  }
                  catch (InterruptedException e)
                  {
                  }
              }
              System.exit(0);
          }
      }

      ---------- END SOURCE ----------

      CUSTOMER SUBMITTED WORKAROUND :
      No easy workaround, if you application continuously creates threads you have a memory leak. The only potential solution would be to recycle threads before they stop, which leads to some excessively complicated coding.

        Attachments

          Activity

            People

            Assignee:
            psoper Pete Soper (Inactive)
            Reporter:
            ndcosta Nelson Dcosta (Inactive)
            Votes:
            0 Vote for this issue
            Watchers:
            1 Start watching this issue

              Dates

              Created:
              Updated:
              Resolved:
              Imported:
              Indexed: