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https://issues.jenkins-ci.org/browse/JENKINS-9882?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=163121#comment-163121
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SCM/JIRA link daemon commented on JENKINS-9882:
-----------------------------------------------
Code changed in jenkins
User: Kohsuke Kawaguchi
Path:
changelog.html
war/pom.xml
http://jenkins-ci.org/commit/jenkins/5a28f6a7f7b3debf3ea2ac459603af0d8086395e
Log:
[FIXED JENKINS-9882] integrated a newer version of Winstone with the fix.
(cherry picked from commit 8eb264ceb1bfdea332009499a06b9faa89dc03e9)
Conflicts:
changelog.html
> Jenkins runs out of file descriptors (winstone problem)
> -------------------------------------------------------
>
> Key: JENKINS-9882
> URL: https://issues.jenkins-ci.org/browse/JENKINS-9882
> Project: Jenkins
> Issue Type: Bug
> Components: core
> Affects Versions: current
> Environment: Environment: Debian 5, sun-java-jdk (1.6.0_22)
> Jenkins version: 1.414-SNAPSHOT
> Reporter: Santeri Paavolainen
>
> Running Jenkins with the embedded Winstone server for a long time
> under constant load conditions causes file descriptor and thread
> leakage.
> Environment: Debian 5, sun-java-jdk (1.6.0_22)
> Jenkins version: 1.414-SNAPSHOT
> What happens:
> After running for about 1 day the following appears on jenkins log
> file:
> [Winstone 2011/05/27 07:35:03] - WARNING: Request handler pool limit exceeded
> - waiting for retry
> and a bit later (this starts repeating):
> [Winstone 2011/05/27 07:43:25] - WARNING: Request handler pool limit exceeded
> - waiting for retry
> [Winstone 2011/05/27 07:43:26] - ERROR: Request ignored because there were no
> more request handlers available in the pool
> [Winstone 2011/05/27 07:43:36] - WARNING: Request handler pool limit exceeded
> - waiting for retry
> [Winstone 2011/05/27 07:43:37] - ERROR: Request ignored because there were no
> more request handlers available in the pool
> Jenkins then stops handling requests successfully - at the beginning
> intermittently, but finally basically failing almost all of the
> requests.
> Using VisualVM I can see that there is a thousand RequestHandlerThread
> threads in wait state, and that over 1200 file descriptors are
> currently in use.
> I think the requests start failing because winstone has a this limit:
> private int MAX_REQUEST_HANDLERS_IN_POOL = 1000;
> as it doesn't seem to be running out of available fds (apparently 8192
> is the maximum in this setup).
> When I restart jenkins I can verify a slow buildup of threads and used
> file descriptors:
> * 10 minutes after restart: 136 live threads, 256 fds used
> * 20 minutes: 150 threads, 271 fds
> * 30 minutes: 161 threads, 280 fds
> * 110 minutes: 255 threads, 376 fds
> I've looked at the repository version of winstone, and looking at the
> code there seems to be a race condition in handling of the request
> handler pool.
> When a request is received by ObjectPool.handleRequest, it looks for
> an available request handler from unusedRequestHandlerThreads and
> calls commenceRequestHandling on the available thread.
> commenceRequestHandling in turn does this.notifyAll() to wake up the
> thread. So far so good. However when the thread has finished
> processing the request, it calls
> this.objectPool.releaseRequestHandler(this) and *then* waits. I think
> here's a race condition, since what can happen is that object pool
> called (CALL) and request handler thread (RH) can interleave like
> this:
> # RH (in RequestHandler.run): this.objectPool.releaseRequestHandler(this)
> # RH (in ObjectPool.releaseRequestHandler):
> this.unusedRequestHandlerThreads.add(rh)
> # CALL (in ObjectPool.handleRequest): take RH from unusedRequestHandlerThreads
> # CALL (in ObjectPool.handleRequest): rh.commenceRequestHandling(socket,
> listener);
> # CALL (in RequestHandler.commenceRequestHandling): this.notifyAll()
> # RH (in ObjectPool.run): this.wait()
> Since notify is lost (no waiters), this.wait() in the last step will
> hang forever. This will leak a file descriptor since the socket given
> to be processed is never reclaimed, and threads are effectively lost
> as Winstone will then create more RequestHandlers.
> Now, this is of course a winstone problem, but its development seems
> to be d-e-a-d at least looking at its bug tracker. As long as this
> problem affect Jenkins, I'd still classify it as a Jenkins problem too.
> I've put this into the winstone tracker too:
> https://sourceforge.net/tracker/?func=detail&aid=3308285&group_id=98922&atid=622497
> Workaround: Use Tomcat, not embedded winstone (that's what I'm doing now).
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