On Wed 24 Jul 2013 08:20:56 AM CEST, Mandy Chung wrote:
On 7/24/2013 2:09 PM, Daniel Fuchs wrote:
On 7/24/13 8:01 AM, Mandy Chung wrote:
I am catching up on this thread....
The thread count counts Java threads that are not
hidden. I believe all VM internal threads are hidden
from external API. This test runs in othervm mode and
AFAICT the thread count is expected to be
deterministic. I don't expect the VM will start and
terminate any thread any time.
I agree with David that we should diagnose why there
is one additional thread started before the reset.
If it is the LogManager$Cleaner thread, like David
said, the VM is shutting down while the test is still
running which doesn't quite make sense.
I think that Shanliang's suspicion that a thread might
be still alive if unscheduled just after having called
its barrier.signal() is a very good suggestion. I would
advise calling thread.join() on all threads in
terminateThreads, just to make sure they are all really
dead and not in some comatose state... If Shanliang is
right then the test would be failing because some of
the threads we think are dead are not actually dead yet
- and not because of some new VM thread that nobody can
see :-)
Thanks for pointing that out.
I agree that the test should be changed to call
Thread.join(). There may be other java.lang.management
tests that should also be fixed to call Thread.join.
I've tried using Thread.join() but I am still getting the
thread count discrepancy.
Specifically: 1. 10 worker threads have been successfully
started - mben.getThreadCount() reports 14 and
Thread.getAllStackTraces() returns 14 items --- Thread:
Thread[Signal Dispatcher,9,system] Thread:
Thread[worker-5,5,main] Thread: Thread[worker-7,5,main]
Thread: Thread[worker-9,5,main] Thread:
Thread[worker-12,5,main] Thread: Thread[worker-11,5,main]
Thread: Thread[Reference Handler,10,system] Thread:
Thread[main,5,main] Thread: Thread[worker-10,5,main]
Thread: Thread[worker-8,5,main] Thread:
Thread[Finalizer,8,system] Thread: Thread[worker-6,5,main]
Thread: Thread[worker-13,5,main] Thread:
Thread[worker-4,5,main] --- 2. Terminating 8 threads 3.
After the threads have been terminated (waiting on
Thread.join() for them to die) - mbean.getThreadCount()
reports 7 while Thread.getAllStackTraces() returns only 6
items --- Thread: Thread[Signal Dispatcher,9,system]
Thread: Thread[Finalizer,8,system] Thread:
Thread[worker-12,5,main] Thread: Thread[Reference
Handler,10,system] Thread: Thread[main,5,main] Thread:
Thread[worker-13,5,main] ---
This would almost point to mbean.getThreadCount() reporting
a stale value. Is that possible?
-JB-
Mandy
