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https://issues.apache.org/jira/browse/HBASE-17085?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15662813#comment-15662813
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Duo Zhang commented on HBASE-17085:
-----------------------------------
I used to tried limiting the concurrent sync requests but it did not help. I
think we could try again after this patch is applied.
And there is no duplicated record. It is just a pipeline. In FSHLog we also use
5 threads to do syncing(That's why I limited the number of concurrent sync
requests to 5)
If no concern, let's commit the patch here first? Thanks.
> AsyncFSWAL may issue unnecessary AsyncDFSOutput.sync
> ----------------------------------------------------
>
> Key: HBASE-17085
> URL: https://issues.apache.org/jira/browse/HBASE-17085
> Project: HBase
> Issue Type: Sub-task
> Components: wal
> Affects Versions: 2.0.0
> Reporter: Duo Zhang
> Assignee: Duo Zhang
> Fix For: 2.0.0
>
> Attachments: HBASE-17085-v1.patch, HBASE-17085.patch
>
>
> The problem is in appendAndSync method, we will issue an AsyncDFSOutput.sync
> if syncFutures is not empty. The SyncFutures in syncFutures can only be
> removed after an AsyncDFSOutput.sync comes back, so before the
> AsyncDFSOutput.sync actually returns, we will always issue an
> AsyncDFSOutput.sync after an append even if there is no new sync request.
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