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Posted to dev@hc.apache.org by "Oleg Kalnichevski (JIRA)" <ji...@apache.org> on 2012/10/07 23:34:02 UTC
[jira] [Commented] (HTTPASYNC-29) Orphan I/O dispatcher threads
[ https://issues.apache.org/jira/browse/HTTPASYNC-29?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13471329#comment-13471329 ]
Oleg Kalnichevski commented on HTTPASYNC-29:
--------------------------------------------
Mark,
The I/O reactor that underpins HttpAsyncClient is designed in such a way that it never spawns I/O threads in any situation. If an unexpected (unchecked) exception is thrown by any of the I/O dispatch threads the I/O reactor automatically shuts down and terminates all its threads. At the moment I can't think of any situation when HttpAsyncClient could start leaking threads. The only thing I could think of is that something in application code can start a new instance of HttpAsyncClient without fully shutting down old one(s). Could this be a possibility? The stack traces seem to suggest that the threads are still running and are being blocked inside an epoll call.
Oleg
> Orphan I/O dispatcher threads
> ------------------------------
>
> Key: HTTPASYNC-29
> URL: https://issues.apache.org/jira/browse/HTTPASYNC-29
> Project: HttpComponents HttpAsyncClient
> Issue Type: Bug
> Affects Versions: 4.0-beta2, 4.0-beta3
> Environment: CentOS 5
> Reporter: Mark Greene
>
> I'm seeing a very slow thread leak in my application resulting from the async http client. It takes several days for these threads to amount to anything significant (e.g. 100-300).
> Here is an example of the stack traces of the thread dump:
> "I/O dispatcher 6138" daemon prio=10 tid=0x09644000 nid=0x1137 runnable [0xf2071000]
> java.lang.Thread.State: RUNNABLE
> at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
> at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:210)
> at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
> at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
> - locked <0xa519af78> (a sun.nio.ch.Util$2)
> - locked <0xa519af88> (a java.util.Collections$UnmodifiableSet)
> - locked <0xa519af38> (a sun.nio.ch.EPollSelectorImpl)
> at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
> at org.apache.http.impl.nio.reactor.AbstractIOReactor.execute(AbstractIOReactor.java:259)
> at org.apache.http.impl.nio.reactor.BaseIOReactor.execute(BaseIOReactor.java:106)
> at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor$Worker.run(AbstractMultiworkerIOReactor.java:604)
> at java.lang.Thread.run(Thread.java:662)
> and this one as well:
> "Thread-4612" daemon prio=10 tid=0xf2e11400 nid=0x1b62 runnable [0xf2340000]
> java.lang.Thread.State: RUNNABLE
> at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
> at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:210)
> at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
> at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
> - locked <0xa519dc10> (a sun.nio.ch.Util$2)
> - locked <0xa519dc20> (a java.util.Collections$UnmodifiableSet)
> - locked <0xa519dbd0> (a sun.nio.ch.EPollSelectorImpl)
> at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
> at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor.execute(AbstractMultiworkerIOReactor.java:366)
> at org.apache.http.impl.nio.conn.PoolingClientAsyncConnectionManager.execute(PoolingClientAsyncConnectionManager.java:108)
> at org.apache.http.impl.nio.client.AbstractHttpAsyncClient.doExecute(AbstractHttpAsyncClient.java:464)
> at org.apache.http.impl.nio.client.AbstractHttpAsyncClient.access$000(AbstractHttpAsyncClient.java:101)
> at org.apache.http.impl.nio.client.AbstractHttpAsyncClient$1.run(AbstractHttpAsyncClient.java:485)
> I was originally seeing this issue with beta2 but upgraded to beta3 with no change in behavior. I'm using httpcore 4.2.2. I also saw this issue https://issues.apache.org/jira/browse/HTTPCORE-315 but I don't think that's causing my issue as I'm not using Futures or canceling them. I'm using a callback.
> Additionally in my callbacks (i.e. completed, error, cancelled), I'm renaming the thread so I could figure out which part of my app might be causing this but none of the orphan threads seemed to enter the callback because as you see above, they were not renamed. I also grepped through my logs for the names of the thread and they did not appear to hit any callback.
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