FULL PRODUCT VERSION :
java version " 1.6.0_27 "
Java(TM) SE Runtime Environment (build 1.6.0_27-b07)
Java HotSpot(TM) 64-Bit Server VM (build 20.2-b06, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Linux xxxxx 2.6.32-131.4.1.el6.x86_64 #1 SMP Fri Jun 10 10:54:26 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux


A DESCRIPTION OF THE PROBLEM :
ScheduledThreadPoolExecutor.shutdownNow() returns cancelled tasks as though they were still due to be executed.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Create a ScheduledThreadPoolExecutor. Schedule a task far in the future. Cancel it. Call shutdownNow(). Even though the task has been cancelled, it is returned in the list of yet-to-be-executed tasks.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The list returned by shutdownNow() should be empty, since it should contain only tasks neither executed nor cancelled.
ACTUAL -
The list contains tasks that were cancelled.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.List;

public class TestShutdownNow {

    public static void main(String[] argv) throws Exception {
ScheduledThreadPoolExecutor scheduler = new ScheduledThreadPoolExecutor(1);

Runnable task = new Runnable() {
public void run() {

}
    };
ScheduledFuture<?> future = scheduler.schedule(task, 999, TimeUnit.DAYS);
if (!future.cancel(false)) {
    throw new Exception( " cancel failed " );
}

List<Runnable> pending = scheduler.shutdownNow();
if (pending.size() != 0) {
    throw new Exception( " shutdownNow() returned " + pending.size() + " tasks instead of zero " );
}
    }
}

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

CUSTOMER SUBMITTED WORKAROUND :
Calling shutdown() before shutdownNow() will purge the internal list of tasks such that shutdownNow() will correctly return an empty list.