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https://issues.apache.org/jira/browse/HBASE-22810?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16912993#comment-16912993
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Zheng Hu commented on HBASE-22810:
----------------------------------
Committed the addendum to all branches, Thanks all.
> Initialize an separate ThreadPoolExecutor for taking/restoring snapshot
> ------------------------------------------------------------------------
>
> Key: HBASE-22810
> URL: https://issues.apache.org/jira/browse/HBASE-22810
> Project: HBase
> Issue Type: Improvement
> Reporter: Zheng Hu
> Assignee: Zheng Hu
> Priority: Major
> Fix For: 3.0.0, 1.5.0, 2.3.0, 2.2.1, 2.1.6, 1.3.6, 1.4.11, 2.0.7
>
>
> In EventType class, we have the following definition, means taking snapshot
> & restoring snapshot are use the MASTER_TABLE_OPERATIONS Executor now.
> {code}
> /**
> * Messages originating from Client to Master.<br>
> * C_M_SNAPSHOT_TABLE<br>
> * Client asking Master to snapshot an offline table.
> */
> C_M_SNAPSHOT_TABLE (48, ExecutorType.MASTER_TABLE_OPERATIONS),
> /**
> * Messages originating from Client to Master.<br>
> * C_M_RESTORE_SNAPSHOT<br>
> * Client asking Master to restore a snapshot.
> */
> C_M_RESTORE_SNAPSHOT (49, ExecutorType.MASTER_TABLE_OPERATIONS),
> {code}
> But when I checked the MASTER_TABLE_OPERATIONS thread pool initialization, I
> see :
> {code}
> private void startServiceThreads() throws IOException{
> // ... some other code initializing ....
> // We depend on there being only one instance of this executor running
> // at a time. To do concurrency, would need fencing of enable/disable of
> // tables.
> // Any time changing this maxThreads to > 1, pls see the comment at
> // AccessController#postCompletedCreateTableAction
>
> this.executorService.startExecutorService(ExecutorType.MASTER_TABLE_OPERATIONS,
> 1);
> startProcedureExecutor();
> {code}
> That's to say, for CPs enable or disable table sequencely, we will create
> a ThreadPoolExecutor with threadPoolSize=1. Then we actually cann't
> accomplish the snapshoting concurrence even if they are total difference
> tables, says if there are two table snapshoting request, and the Table A cost
> 5min for snapshoting, then the Table B need to wait 5min and once Table A
> finish its snapshot , then Table B will start the snapshot.
> While we've setting the snapshot timeout, so it will be easy to timeout for
> table B snapshoting . Actually, we can create a separate thead pool for
> snapshot operations only.
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