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https://issues.apache.org/jira/browse/HTTPCORE-433?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Oleg Kalnichevski updated HTTPCORE-433:
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Fix Version/s: 4.4.6
You are correct. The stale connection check is likely to be too expensive to
execute within the lock protected execution path without causing lock
contention.
Oleg
PS: We happily take patches
> 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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