Name: rmT116609 Date: 02/08/2004


FULL PRODUCT VERSION :
java version "1.5.0-beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-beta-b32c)
Java HotSpot(TM) Client VM (build 1.5.0-beta-b32c, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Windows XP [Version 5.1.2600]


A DESCRIPTION OF THE PROBLEM :
A java.util.concurrent thread pool may consume cpu after all work has been done. I'm seeing 100% CPU usage after completing all jobs.
Thread dumps reveal that one thread sometimes is to be seen awake, checking its interruption status when it should be parked and sleeping:

"pool-1-thread-2" prio=5 tid=0x008edca0 nid=0x984 runnable [0x0135f000..0x0135fb
68]
        at java.lang.Thread.isInterrupted(Native Method)
        at java.lang.Thread.interrupted(Unknown Source)
        at java.util.concurrent.locks.ReentrantLock$ConditionObject.await(Unknow
n Source)
        at java.util.concurrent.LinkedBlockingQueue.take(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor.getTask(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor.access+100(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)




STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the testcase with a fair number of threads. On my machine '10' is always sufficient, sometimes '3' are enough.


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The program should print a decreasing sequence of numbers and then remain idle.
ACTUAL -
The program prints a decreasing sequence of numbers and then consumes 100% CPU.


REPRODUCIBILITY :
This bug can be reproduced often.

---------- BEGIN SOURCE ----------
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.atomic.AtomicInteger;

public class ThreadPool {
  public static void main(String[] args) {
    int n = Integer.parseInt(args[0]);
    final AtomicInteger todo = new AtomicInteger(2*n);

    ExecutorService p = Executors.newFixedThreadPool(n);
    for(int i=0; i<2*n; i++) {
      p.execute(new Runnable() { public void run() {
System.out.println(todo.decrementAndGet());
      }});
    }
  }
}

---------- END SOURCE ----------
(Incident Review ID: 237713)
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