Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-6801020

Concurrent Semaphore release may cause some require thread not signaled

    XMLWordPrintable

    Details

    • Type: Bug
    • Status: Closed
    • Priority: P2
    • Resolution: Fixed
    • Affects Version/s: 6u11, 6u17
    • Fix Version/s: 7
    • Component/s: core-libs
    • Labels:
    • Subcomponent:
    • Resolved In Build:
      b55
    • CPU:
      x86, sparc
    • OS:
      solaris_10, windows_xp
    • Verification:
      Verified

      Backports

        Description

        FULL PRODUCT VERSION :
        java version "1.6.0_11"
        Java(TM) SE Runtime Environment (build 1.6.0_11-b03)
        Java HotSpot(TM) Client VM (build 11.0-b16, mixed mode, sharing)

        ADDITIONAL OS VERSION INFORMATION :
        Windows XP SP3

        EXTRA RELEVANT SYSTEM CONFIGURATION :
        P4 2.8HT

        A DESCRIPTION OF THE PROBLEM :
        Semaphore initial state 0. 4 threads run 4 tasks.
        Two threads run acquire semaphore once, the other two threads run release semaphore once.
        One possible result is the semaphore state value is 1 and one thread still waiting.

        The possible reason:
        When AbstractQueuedSynchronizer#release are called, head.waitStatus may be 0 because the previous acquire thread may run at AbstractQueuedSynchronizer#doAcquireShared before setHeadAndPropagate is called.

        STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
        The given executable test case will hung. Suggest using dual-core CPU or HT CPU to reproduce.


        REPRODUCIBILITY :
        This bug can be reproduced occasionally.

        ---------- BEGIN SOURCE ----------
        import java.util.concurrent.Semaphore;

        public class TestSemaphore {

            private static Semaphore sem = new Semaphore(0);

            private static class Thread1 extends Thread {
                @Override
                public void run() {
                    sem.acquireUninterruptibly();
                }
            }

            private static class Thread2 extends Thread {
                @Override
                public void run() {
                    sem.release();
                }
            }

            public static void main(String[] args) throws InterruptedException {
                for (int i = 0; i < 10000000; i++) {
                    Thread t1 = new Thread1();
                    Thread t2 = new Thread1();
                    Thread t3 = new Thread2();
                    Thread t4 = new Thread2();
                    t1.start();
                    t2.start();
                    t3.start();
                    t4.start();
                    t1.join();
                    t2.join();
                    t3.join();
                    t4.join();
                    System.out.println(i);
                }
            }
        }

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

          Attachments

            Issue Links

              Activity

                People

                Assignee:
                dholmes David Holmes
                Reporter:
                ndcosta Nelson Dcosta (Inactive)
                Votes:
                0 Vote for this issue
                Watchers:
                2 Start watching this issue

                  Dates

                  Created:
                  Updated:
                  Resolved:
                  Imported:
                  Indexed: