[jira] [Updated] (HBASE-8729) distributedLogReplay may hang during chained region server failure

["Jeffrey Zhong (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-8729?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jeffrey Zhong updated HBASE-8729:
---------------------------------

      Resolution: Fixed
    Hadoop Flags: Reviewed
          Status: Resolved  (was: Patch Available)
    
> 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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