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https://issues.apache.org/jira/browse/HDFS-12412?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andrew Wang updated HDFS-12412:
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    Labels: hdfs-ec-3.0-nice-to-have  (was: )

> Remove ErasureCodingWorker.stripedReadPool
> ------------------------------------------
>
>                 Key: HDFS-12412
>                 URL: https://issues.apache.org/jira/browse/HDFS-12412
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: erasure-coding
>    Affects Versions: 3.0.0-alpha3
>            Reporter: Lei (Eddy) Xu
>            Assignee: Lei (Eddy) Xu
>              Labels: hdfs-ec-3.0-nice-to-have
>
> In {{ErasureCodingWorker}}, it uses {{stripedReconstructionPool}} to schedule 
> the EC recovery tasks, while uses {{stripedReadPool}} for the reader threads 
> in each recovery task.  We only need one of them to throttle the speed of 
> recovery process, because each EC recovery task has a fix number of source 
> readers (i.e., 3 for RS(3,2)). And because of the findings in HDFS-12044, the 
> speed of EC recovery can be throttled by {{strippedReconstructionPool}} with 
> {{xmitsInProgress}}. 
> Moreover, keeping {{stripedReadPool}} makes customer difficult to understand 
> and calculate the right balance between 
> {{dfs.datanode.ec.reconstruction.stripedread.threads}}, 
> {{dfs.datanode.ec.reconstruction.stripedblock.threads.size}} and 
> {{maxReplicationStreams}}.  For example, a small {{stripread.threads}} 
> (comparing to which {{reconstruction.threads.size}} implies), will 
> unnecessarily limit the speed of recovery, which leads to larger MTTR. 



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