slump wrote:
> Anyone can answer this?
> If I am wrong, please tell me
>
No time to check atm. Can you create a JIRA with your first message ? We
will process it later (mails get lost, when JIRA stay in our way...)
Thanks !
> Thanks
>
>
>
>
> slump
> 2008-09-28
>
>
>
> 发件人： slump
> 发送时间： 2008-09-04 17:30:35
> 收件人： dev
> 抄送：
> 主题： race condition in OrderedThreadPoolExecutor/UnorderedThreadPoolExecutor
>
>
> I think I found a race condition in
> OrderedThreadPoolExecutor/UnorderedThreadPoolExecutor
>
> I write a textline echo server using MINA
>
> I add a UnorderedThreadPoolExecutor in server's filter:
>
> acceptor.getFilterChain().addLast("executor",
> new ExecutorFilter(new UnorderedThreadPoolExecutor(10)));
>
> and in messageReceived, I add sleep(3000) before echo the line received
>
> when I send 10 lines from client , I think the server should use 10 threads
> to process 10 message concurrently
> but the server only use 2 thread or 4 thread , and the remain message must
> wait until sleep complete
>
> I changed executor to ThreadPoolExecutor in JDK, it will use 10 thread
>
> I checked and trace the code of UnorderedThreadPoolExecutor, find the reason:
> private void addWorkerIfNecessary() {
> if (idleWorkers.get() == 0) {
> synchronized (workers) {
> if (workers.isEmpty() || idleWorkers.get() == 0) {
> addWorker();
> }
> }
> }
> }
>
> there may be some race condition:
> 1 thread A call executor's execute to sunmit one task
> 2 executor find there are no idle worker, so create a new thread and start
> it, now idleWorkers is 1
> 3 before new worker thread fetch task and decrement the idleWorkers, the
> thread A submit more task
> 4 the executor find idleWorkers is 1 , so don't create new thread
> 5 the new worker thread fetch task and decrement the idleWorkers, now
> idleWorkers is 0 ,but there are some task left in queue without worker
>
> MAYBE the idleWorkers.get() == 0 should be change to idleWorkers.get() <
> getQueue().size() ?
>
> And in OrderedThreadPoolExecutor , have the same race condition.
>
>
> And I have one more question:
> Why not just use ThreadPoolExecutor in JDK instead of
> UnorderedThreadPoolExecutor?
> does UnorderedThreadPoolExecutor have some special requirement which
> ThreadPoolExecutor can't fulfil?
>
>
>
>
> dingli
> 2008-09-04
>
--
--
cordialement, regards,
Emmanuel Lécharny
www.iktek.com
directory.apache.org
