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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-5299) DFS client hangs in updatePipeline RPC when failover happened
Date Mon, 07 Oct 2013 13:32:49 GMT

    [ https://issues.apache.org/jira/browse/HDFS-5299?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13788134#comment-13788134
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Hudson commented on HDFS-5299:
------------------------------

SUCCESS: Integrated in Hadoop-Hdfs-trunk #1545 (See [https://builds.apache.org/job/Hadoop-Hdfs-trunk/1545/])
HDFS-5299. DFS client hangs in updatePipeline RPC when failover happened. Contributed by Vinay.
(jing9: http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1529660)
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNamenodeRetryCache.java


> DFS client hangs in updatePipeline RPC when failover happened
> -------------------------------------------------------------
>
>                 Key: HDFS-5299
>                 URL: https://issues.apache.org/jira/browse/HDFS-5299
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>    Affects Versions: 3.0.0, 2.1.0-beta
>            Reporter: Vinay
>            Assignee: Vinay
>            Priority: Blocker
>             Fix For: 2.2.0
>
>         Attachments: HDFS-5299.000.patch, HDFS-5299.patch
>
>
> DFSClient got hanged in updatedPipeline call to namenode when the failover happened at
exactly sametime.
> When we digged down, issue found to be with handling the RetryCache in updatePipeline.
> Here are the steps :
> 1. Client was writing slowly.
> 2. One of the datanode was down and updatePipeline was called to ANN.
> 3. Call reached the ANN, while processing updatePipeline call it got shutdown.
> 3. Now Client retried (Since the api marked as AtMostOnce) to another NameNode. at that
time still NN was in STANDBY and got StandbyException.
> 4. Now one more time client failover happened. 
> 5. Now SNN became Active.
> 6. Client called to current ANN again for updatePipeline, 
> Now client call got hanged in NN, waiting for the cached call with same callid to be
over. But this cached call is already got over last time with StandbyException.
> Conclusion :
> Always whenever the new entry is added to cache we need to update the result of the call
before returning the call or throwing exception.
> I can see similar issue multiple RPCs in FSNameSystem.



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