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https://issues.apache.org/jira/browse/HDFS-12412?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16164002#comment-16164002
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Hudson commented on HDFS-12412:
-------------------------------
SUCCESS: Integrated in Jenkins build Hadoop-trunk-Commit #12857 (See
[https://builds.apache.org/job/Hadoop-trunk-Commit/12857/])
HDFS-12412. Change ErasureCodingWorker.stripedReadPool to cached thread (lei:
rev 123342cd0759ff88801d4f5ab10987f6e3f344b0)
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
* (edit) hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSErasureCoding.md
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/erasurecode/ErasureCodingWorker.java
* (edit) hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml
> Change ErasureCodingWorker.stripedReadPool to cached thread pool
> ----------------------------------------------------------------
>
> 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
> Fix For: 3.0.0-beta1
>
> Attachments: HDFS-12412.00.patch, HDFS-12412.01.patch
>
>
> 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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