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  1. JDK
  2. JDK-4329256

interrupted thread no longer produces output (sol)

    Details

    • Type: Bug
    • Status: Closed
    • Priority: P4
    • Resolution: Not an Issue
    • Affects Version/s: 1.3.0, 5.0, 6
    • Fix Version/s: None
    • Component/s: core-libs
    • Labels:
    • Subcomponent:
    • CPU:
      generic, sparc
    • OS:
      solaris_2.5.1, solaris_8, solaris_9

      Description

      Name: rlT66838 Date: 04/10/2000


      java version "1.3.0rc2"
      Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0rc2-Y)

      An interrupted thread appears not to be able to produce output through
      System.err and System.out. This remains the case while the 'interrupted' flag is
      set. Once the 'interrupted' flag has been cleared (either by a call to
      Thread.interrupted or to an 'interruptable' method such as Thread.sleep), the
      thread produces output normally.

      Below is a Java class that demonstrates the problem.'java InterruptBug yes' runs
      a thread which is (immediately) interrupted. 'java InterruptBug no' runs a
      thread which is not interrupted. In both cases the thread repeatedly (once every
      second, for five seconds) checks and prints the outcome of 'isInterrupted()'.
      After that, it does the same for 'interrupted()'.

      The 'no' version will produce correct output during the full ten seconds.
      However the 'yes' version will buffer its output during the first five or six
      seconds. Then, after clearing the 'interrupted' flag, the buffered output is
      printed, followed by the remaining output.

      Output of the 'no version':

      bash-2.00$ java InterruptBug no
      not interrupting
      isInterrupted: false
      isInterrupted: false
      isInterrupted: false
      isInterrupted: false
      isInterrupted: false
      interrupted: false
      interrupted: false
      interrupted: false
      interrupted: false
      interrupted: false

      Output of the 'yes' version:

      bash-2.00$ java InterruptBug yes
      interrupting
      isInterrupted: true
      isInterrupted: true
      isInterrupted: true
      isInterrupted: true
      isInterrupted: true
      interrupted: true
      interrupted: false
      interrupted: false
      interrupted: false
      interrupted: false

      Note that the 'yes' output shown above is correct. However there is a delay,
      which is incorrect.

      public class InterruptBug implements Runnable
      {
        public static void main (String[] args)
        {
           if (args.length != 1) {
             System.err.println ("Usage: InterruptBug [yes|no]");
             return;
           }
           boolean do_interrupt = "yes".equals (args [0]);

           Thread t = new Thread (new InterruptBug());
           t.start();
           if (do_interrupt) {
             System.out.println ("interrupting");
             t.interrupt();
           }
           else
             System.out.println ("not interrupting");
        }

        public void run()
        {
          // for five seconds, repeatedly check the 'interrupted' flag
          for (int j = 0; j < 5; j++) {
            sleep (1000);
            if (Thread.currentThread().isInterrupted())
              System.out.println ("isInterrupted: true");
            else
              System.out.println ("isInterrupted: false");
          }

          // for five seconds, repeatedly check and clear the 'interrupted' flag
          for (int j = 0; j < 5; j++) {
            sleep (1000);
            if (Thread.interrupted())
              System.out.println ("interrupted: true");
            else
              System.out.println ("interrupted: false");
          }
        }

        /** Sleep without using Thread.sleep. */
        private static void sleep (long millis)
        {
          long end_time = System.currentTimeMillis() + millis;
          while (System.currentTimeMillis() < end_time)
            ;
        }
      }
      (Review ID: 103479)
      ======================================================================

      Name: yy116575 Date: 02/15/2001

      Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0)
      Java HotSpot(TM) Client VM (build 1.3.0, mixed mode)


      Calling System.out.println clears the interrupted flag for the thread.

      The following example code has the following output:

      Before => true
      After => false

      public class junk {
        public static void main(String[] args) {
          try {
            Thread.currentThread().interrupt();
            boolean keepInterrupted = Thread.currentThread().isInterrupted();

            System.out.println(); // This blank line disappears.
            System.out.println("Before => " + keepInterrupted);
            System.out.println("After => " + Thread.currentThread().isInterrupted());

          } catch (Exception e) {
            e.printStackTrace();
          }
        }
      }
      (Review ID: 117079)
      ======================================================================

      In the first test case, if the output is flushed then it appears immediately
      but that seems to clear the interrupted status:
      > java InterruptBug yes
      interrupting
      isInterrupted: true
      isInterrupted: false
      isInterrupted: false
      isInterrupted: false
      isInterrupted: false
      interrupted: false
      interrupted: false
      interrupted: false
      interrupted: false
      interrupted: false

      This doesn't occur on Linux.

      michael.mccloskey@eng 2001-04-03

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              • Assignee:
                Unassigned
                Reporter:
                rlewis Roger Lewis (Inactive)
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