I finally proposed a patch for trunk in
https://issues.apache.org/bugzilla/show_bug.cgi?id=49159 for this. Thanks for
reviewing it...
Sylvain
On 30 avr. 2010, at 18:27, Sylvain Laurent wrote:
>
> On 30 avr. 2010, at 00:01, Pid wrote:
>>
>> Are you saying that you want to stop processing requests each time a
>> webapp gets restarted, or that the thread pool is refreshed by
>> sequentially killing each thread and recreating it?
>
> Something in between : I create a new pool with the same characteristics as
> the current one, make it the current pool so that new requests are served by
> the new pool, then cleanly shut the old pool down. When calling
> ThreadPoolExecutor.shutdown(), it gracefully terminates all threads in the
> pool after its associated TaskQueue is empty : Idle threads stop immediately
> (and not sequentially), busy threads continue processing their current
> request. If the TaskQueue is not empty, it means that there are no idle
> threads, and so busy threads will continue processing tasks in the queue
> until it becomes empty.
>
> The renewThreads looks like (in StandardThreadExecutor) :
>
> public void renewThreads() {
> ThreadPoolExecutor oldExecutor;
> synchronized (executorLock) { // to avoid renewing threads
> concurrently
> oldExecutor = executor;
> ThreadPoolExecutor newExecutor=new
> ThreadPoolExecutor(getMinSpareThreads(),
> getMaxThreads(), maxIdleTime,
> TimeUnit.MILLISECONDS,
> taskqueue,
> oldExecutor.getThreadFactory());
>
> executor = newExecutor;
> taskqueue.setParent(executor);
> }
>
> oldExecutor.shutdown();
> //we don't wait for termination of the old pool, threads will
> terminate when their work is done
> }
>
> I marked StandardThreadExecutor.executor and TaskQueue.parent as volatile to
> propagate the change of executor instance to other threads without
> synchronizing threads.
>
> An improvement I can do is to pre-start some "core" threads in the new pool
> before making it active. It would reduce the performance impact on the next
> few requests.
>
> Sylvain
>
>
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