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https://issues.apache.org/jira/browse/HAWQ-1030?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ming LI resolved HAWQ-1030.
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Resolution: Fixed
> User hang due to poor spin-lock/LWLock performance under high concurrency
> -------------------------------------------------------------------------
>
> Key: HAWQ-1030
> URL: https://issues.apache.org/jira/browse/HAWQ-1030
> Project: Apache HAWQ
> Issue Type: Bug
> Components: Core
> Reporter: Ming LI
> Assignee: Ming LI
> Fix For: 2.0.1.0-incubating
>
>
> Some clients have recently reported apparent hangs with their applications.
> In all cases the symptoms were the same:
> * All sessions appear to be hung in LWLockAcquire or Release, specifically
> s_lock
> * there is a high number of concurrent sessions (close to 100)
> * System is not actually hung, normally processing resumes after some period
> of time when all sessions have completed their locking work
> The postgresql developer community has found several issues with performance
> under high concurrency (> 32 sessions) in the spin-lock mechanism we've
> inherited in HAWQ. This ultimately has been corrected in 9.5 with a
> replacement to the spin-lock mechanism and appears to provide a significant
> boost to query performance.
> The actual fix is in commit: ab5194e6f617a9a9e7aadb3dd1cee948a42d0755
> Only 1 line commit to s_lock.c could help address this and would be easy
> enough to cherry-pick: b03d196be055450c7260749f17347c2d066b4254
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