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https://issues.apache.org/jira/browse/HDFS-12044?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16105422#comment-16105422
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Hudson commented on HDFS-12044:
-------------------------------

SUCCESS: Integrated in Jenkins build Hadoop-trunk-Commit #12068 (See 
[https://builds.apache.org/job/Hadoop-trunk-Commit/12068/])
HDFS-12044. Mismatch between BlockManager.maxReplicationStreams and (lei: rev 
77791e4c36ddc9305306c83806bf486d4d32575d)
* (edit) 
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
* (edit) 
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/erasurecode/StripedBlockReconstructor.java
* (edit) 
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/erasurecode/StripedReader.java
* (edit) 
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/erasurecode/StripedReconstructor.java
* (edit) 
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSUtilClient.java
* (edit) 
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestReconstructStripedFile.java
* (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/java/org/apache/hadoop/hdfs/server/datanode/erasurecode/StripedReconstructionInfo.java


> Mismatch between BlockManager#maxReplicationStreams and 
> ErasureCodingWorker.stripedReconstructionPool pool size causes slow and 
> bursty recovery
> -----------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-12044
>                 URL: https://issues.apache.org/jira/browse/HDFS-12044
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: erasure-coding
>    Affects Versions: 3.0.0-alpha3
>            Reporter: Lei (Eddy) Xu
>            Assignee: Lei (Eddy) Xu
>              Labels: hdfs-ec-3.0-must-do
>             Fix For: 3.0.0-beta1
>
>         Attachments: HDFS-12044.00.patch, HDFS-12044.01.patch, 
> HDFS-12044.02.patch, HDFS-12044.03.patch, HDFS-12044.04.patch, 
> HDFS-12044.05.patch
>
>
> {{ErasureCodingWorker#stripedReconstructionPool}} is with {{corePoolSize=2}} 
> and {{maxPoolSize=8}} as default. And it rejects more tasks if the queue is 
> full.
> When {{BlockManager#maxReplicationStream}} is larger than 
> {{ErasureCodingWorker#stripedReconstructionPool#corePoolSize/maxPoolSize}}, 
> for example, {{maxReplicationStream=20}} and {{corePoolSize=2 , 
> maxPoolSize=8}}.  Meanwhile, NN sends up to {{maxTransfer}} reconstruction 
> tasks to DN for each heartbeat, and it is calculated in {{FSNamesystem}}:
> {code}
> final int maxTransfer = blockManager.getMaxReplicationStreams() - 
> xmitsInProgress;
> {code}
> However, at any giving time, 
> {{{ErasureCodingWorker#stripedReconstructionPool}} takes 2 {{xmitInProcess}}. 
> So for each heartbeat in 3s, NN will send about {{20-2 = 18}} reconstruction 
> tasks to the DN, and DN throw away most of them if there were 8 tasks in the 
> queue already. So NN needs to take longer to re-consider these blocks were 
> under-replicated to schedule new tasks.



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