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https://issues.apache.org/jira/browse/HBASE-8729?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13700508#comment-13700508
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Jeffrey Zhong commented on HBASE-8729:
--------------------------------------
Thanks [[email protected]] and [[email protected]] for reviews! I've
integrated the change into 0.95 & trunk branches.
{quote}
rather than ask if lock is 'locked' and unlock it if current thread matches the
lock 'owner'?
{quote}
needReleaseLock is a local boolean variable so other threads won't see its
value of current thread. Therefore other threads won't release splitLogLock
without really owning it. The downside of checking lock 'owner' needs to cast
splitLogLock down to ReentrantLock type.
> distributedLogReplay may hang during chained region server failure
> ------------------------------------------------------------------
>
> Key: HBASE-8729
> URL: https://issues.apache.org/jira/browse/HBASE-8729
> Project: HBase
> Issue Type: Bug
> Components: MTTR
> Reporter: Jeffrey Zhong
> Assignee: Jeffrey Zhong
> Fix For: 0.98.0, 0.95.2
>
> Attachments: 8729-v2.patch, hbase-8729.patch, hbase-8729-v3.patch,
> hbase-8729-v4.patch, hbase-8729-v5.patch
>
>
> In a test, half cluster(in terms of region servers) was down and some log
> replay had incurred chained RS failures(receiving RS of a log replay failed
> again).
> Since by default, we only allow 3 concurrent SSH handlers(controlled by
> {code}this.executorService.startExecutorService(ExecutorType.MASTER_SERVER_OPERATIONS,conf.getInt("hbase.master.executor.serverops.threads",
> 3));{code}).
> If all 3 SSH handlers are doing logReplay(blocking call) and one of receiving
> RS fails again then logReplay will hang because regions of the newly failed
> RS can't be re-assigned to another live RS(no ssh handler will be processed
> due to max threads setting) and existing log replay will keep routing replay
> traffic to the dead RS.
> The fix is to submit logReplay work into a separate type of executor queue in
> order not to block SSH region assignment so that logReplay can route traffic
> to a live RS after retries and move forward.
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