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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, 24 Sep 2016 09:32:20 GMT

    [ https://issues.apache.org/jira/browse/HTTPCORE-433?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15518758#comment-15518758
] 

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

Sergiu
Could you please test the following patch and let me know if that fixes the problem for you?
https://github.com/ok2c/httpcore/commit/b1e6ec7b80efced8e315b722a734c178ab19697a

Oleg

> 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
>
>         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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