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

["Ted Yu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-8729?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13680420#comment-13680420 ] 

Ted Yu commented on HBASE-8729:
-------------------------------

{code}
+    this.executorService.startExecutorService(ExecutorType.MASTER_LOG_REPLAY_OPERATIONS,
+      conf.getInt("hbase.master.executor.serverops.threads", 15));
{code}
Did you intend to introduce a new config param for log replay operations ?

There are several syntax errors in class javadoc for EventHandler.
{code}
+    sinkConf.setInt(HConstants.HBASE_RPC_TIMEOUT_KEY, HConstants.DEFAULT_HBASE_RPC_TIMEOUT / 2);
{code}
Can you add some comment for the above change ?
                
> 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: hbase-8729.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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