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https://issues.apache.org/jira/browse/HDFS-9494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15116748#comment-15116748
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GAO Rui commented on HDFS-9494:
-------------------------------

[~szetszwo],[~rakeshr], thanks a lot for your advice. For 
{{executor.shutdownNow()}}, if not all the tasks had been completed, we might 
not arrive to the end of {{flushAllInternals()}}. But there is no harmless to 
ensure executor shutdown, so I add {{executor.shutdownNow()}} as well.   

After checking the related codes, it seems that we haven't set a timeout for 
{{waitForAckedSeqno()}}. Maybe we could consider to set a timeout for it in 
another new Jira. I have updated the 05 patch. Could you kindly review it? 
Thank you very much.

> Parallel optimization of DFSStripedOutputStream#flushAllInternals( )
> --------------------------------------------------------------------
>
>                 Key: HDFS-9494
>                 URL: https://issues.apache.org/jira/browse/HDFS-9494
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>            Reporter: GAO Rui
>            Assignee: GAO Rui
>            Priority: Minor
>         Attachments: HDFS-9494-origin-trunk.00.patch, 
> HDFS-9494-origin-trunk.01.patch, HDFS-9494-origin-trunk.02.patch, 
> HDFS-9494-origin-trunk.03.patch, HDFS-9494-origin-trunk.04.patch, 
> HDFS-9494-origin-trunk.05.patch
>
>
> Currently, in DFSStripedOutputStream#flushAllInternals( ), we trigger and 
> wait for flushInternal( ) in sequence. So the runtime flow is like:
> {code}
> Streamer0#flushInternal( )
> Streamer0#waitForAckedSeqno( )
> Streamer1#flushInternal( )
> Streamer1#waitForAckedSeqno( )
> …
> Streamer8#flushInternal( )
> Streamer8#waitForAckedSeqno( )
> {code}
> It could be better to trigger all the streamers to flushInternal( ) and
> wait for all of them to return from waitForAckedSeqno( ),  and then 
> flushAllInternals( ) returns.



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