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Date: Sat, 24 Sep 2016 15:17:20 +0000 (UTC)
From: "Oleg Kalnichevski (JIRA)" <jira@apache.org>
To: dev@hc.apache.org
Message-ID: <JIRA.13005920.1474294620000.656070.1474730240599@Atlassian.JIRA>
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References: <JIRA.13005920.1474294620000@Atlassian.JIRA> <JIRA.13005920.1474294620474@arcas>
Subject: [jira] [Updated] (HTTPCORE-433) Setting validateAfterInactivity to
 1ms increases lock contention in AbstractConnPool
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archived-at: Sat, 24 Sep 2016 15:17:22 -0000


     [ https://issues.apache.org/jira/browse/HTTPCORE-433?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Oleg Kalnichevski updated HTTPCORE-433:
---------------------------------------
    Fix Version/s:     (was: 4.4.6)
                   5.0

> 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: 5.0
>
>         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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