ScheduledExecutorService does not work as we expect.

The test programs schedules the execution of MyTask().
--
When Mytask() is scheduled  in scheduleWithFixedDelay() as follows,
 -initialDelay is 0 : Execute right now
 -delay is 1000[msec] : Execute every 1000[msec]
the MyTask() sometimes is not executed.
Initial execution of MyTask() is not executed and scheduled MyTask() is not executed also.

CONFIGURATION:
OS : WindowsXP(SP2,Japanese)
JRE/JDK : jdk7b30/jdk6u7/jdk5u16

Note:
 The reporter says, this occus in RHEL(x86) and submitter confirms this problem occurs in Solaris10.

FREQUENCY:
 The problem can be reproducible so often. 
The test program sometimes finishes correctly.

EXPECTED:
 The followings message will shows up.

ACTUAL:
 No message. The execution seems hang.
Posted Date : 2008-07-15 08:22:44.0

Avoid using delays far in the future.

As the submitter had determined the various "schedule" methods contain code of the form:

long triggerTime = now() + delay;

and if the delay is sufficiently large then overflow will occur.

When overflow occurs a negative delay-time can be stored into the delay-queue and this causes the delay queue to operate incorrectly. If you place a correct entry in the queue and then add a negative entry, while the correct entry is still there, then the correct entry is pushed down and no task ever becomes scheduled to run - and we have the hang as reported.

However, if the correct task is removed from the queue by a worker thread, prior to the negative task being submitted, then the task is correctly replaced in the queue and the test passes.

It was curious to find that:

java Test

passes, while

java -showversion Test

always hangs.
Posted Date : 2008-07-17 07:10:30.0

There is actually a more subtle underlying issue with the data structure that hides a number of potential bugs. Martin Buchholz has prepared a complete fix for delivery in to OpenJDK.
Posted Date : 2008-07-28 04:46:26.0

http://hg.openjdk.java.net/jdk7/tl/jdk/rev/f33c3846cecb
Posted Date : 2008-08-01 10:18:53.0