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https://issues.apache.org/jira/browse/SOLR-4509?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14231190#comment-14231190
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Oleg Kalnichevski commented on SOLR-4509:
-----------------------------------------

The idea behind connection check optimizations in HC 4.4 is rather 
straight-forward: given the 'stale' check cannot be 100% reliable (the 
connection can turn 'stale' immediately after passing the check but before a 
request is issued) there is no point checking the connection indiscriminately 
before each and every request. It generally should be sufficient to check those 
connections that are more likely to get 'stale'. Usually those are the 
connections that have been sitting idle in the connection pool for a 
considerable period of time.

HC 4.4 is most likely going to get delayed by a month or two. So, there should 
enough time to contribute an alternative solution if it turns out to be better 
than what we currently have.

Oleg

> Disable HttpClient stale check for performance and fewer spurious connection 
> errors.
> ------------------------------------------------------------------------------------
>
>                 Key: SOLR-4509
>                 URL: https://issues.apache.org/jira/browse/SOLR-4509
>             Project: Solr
>          Issue Type: Improvement
>          Components: search
>         Environment: 5 node SmartOS cluster (all nodes living in same global 
> zone - i.e. same physical machine)
>            Reporter: Ryan Zezeski
>            Assignee: Mark Miller
>            Priority: Minor
>             Fix For: 5.0, Trunk
>
>         Attachments: IsStaleTime.java, SOLR-4509-4_4_0.patch, 
> SOLR-4509.patch, SOLR-4509.patch, SOLR-4509.patch, SOLR-4509.patch, 
> SOLR-4509.patch, baremetal-stale-nostale-med-latency.dat, 
> baremetal-stale-nostale-med-latency.svg, 
> baremetal-stale-nostale-throughput.dat, baremetal-stale-nostale-throughput.svg
>
>
> By disabling the Apache HTTP Client stale check I've witnessed a 2-4x 
> increase in throughput and reduction of over 100ms.  This patch was made in 
> the context of a project I'm leading, called Yokozuna, which relies on 
> distributed search.
> Here's the patch on Yokozuna: https://github.com/rzezeski/yokozuna/pull/26
> Here's a write-up I did on my findings: 
> http://www.zinascii.com/2013/solr-distributed-search-and-the-stale-check.html
> I'm happy to answer any questions or make changes to the patch to make it 
> acceptable.
> ReviewBoard: https://reviews.apache.org/r/28393/



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