[
https://issues.apache.org/jira/browse/HAWQ-1030?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15447862#comment-15447862
]
Ming LI commented on HAWQ-1030:
-------------------------------
Hawq didn't change the implementation of spin lock which is same with
postgresql, thinking that porting from new version of postgresql in the future,
here we keep the code more similar to latest postgresql (version 9.6).
> 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
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
