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From "Oleg Kalnichevski (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HTTPCORE-433) Setting validateAfterInactivity to 1ms increases lock contention in AbstractConnPool
Date Sat, 19 Nov 2016 18:50:58 GMT

    [ https://issues.apache.org/jira/browse/HTTPCORE-433?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15679689#comment-15679689
] 

Oleg Kalnichevski commented on HTTPCORE-433:
--------------------------------------------

Sergiu
Could you please try out the patch [2] from this branch [1] and let me know if it solves the
problem for you?

Oleg

[1] https://github.com/ok2c/httpcore/tree/HTTPCORE-433
[2] https://github.com/apache/httpcore/compare/4.4.x...ok2c:HTTPCORE-433 

> Setting validateAfterInactivity to 1ms increases lock contention in AbstractConnPool
> ------------------------------------------------------------------------------------
>
>                 Key: HTTPCORE-433
>                 URL: https://issues.apache.org/jira/browse/HTTPCORE-433
>             Project: HttpComponents HttpCore
>          Issue Type: Bug
>          Components: HttpCore
>    Affects Versions: 4.4.4
>            Reporter: Sergiu Prodan
>             Fix For: 4.4.6, 5.0-alpha2
>
>         Attachments: httpclient_thread_dump, threads_when_inactivity_set_to_1.png, threads_when_inactivity_set_to_2000.png
>
>
> This issue was observed after upgrading to httpclient v4.5.2 and httpcore v4.4.4. 
> When configuring the PoolingHttpClientConnectionManager, I have set validateAfterInactivity
to 1ms as this is the only way of maintaining the old behaviour, i.e. checking every connection
if is stale before using it.
> I have observed a performance degradation under high load when the httpclient is shared
between multiple threads. This httpclient is used only for one route.
> After taking a thread dump, one thing that got my attention was several threads waiting
for same ReentrantLock instance while trying to AbstractConnPool#getPoolEntryBlocking/AbstractConnPool#release.
The ReentrantLock instance in question was owned by another thread performing CPool#validate.
> It seems to me that performing this stale check inside the region protected by this lock
is unnecessary and also induces a big performance hit when using the httpclient from multiple
threads.
> I've atached a thread dump of a test application that reproduces this behaviour. ReentrantLock
in question in this thread dump is 0x0000000706e8b9a8 and is owned by Thread-4.



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