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Date: Sat, 2 May 2015 04:37:10 +0000 (UTC)
From: "Hadoop QA (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (HDFS-4273) Fix some issue in DFSInputstream
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    [ https://issues.apache.org/jira/browse/HDFS-4273?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14524762#comment-14524762 ] 

Hadoop QA commented on HDFS-4273:
---------------------------------

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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:red}-1{color} | patch |   0m  0s | The patch command could not apply the patch during dryrun. |
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|| Subsystem || Report/Notes ||
| Patch URL | http://issues.apache.org/jira/secure/attachment/12621932/HDFS-4273.v8.patch |
| Optional Tests | javadoc javac unit findbugs checkstyle |
| git revision | trunk / f1a152c |
| Console output | https://builds.apache.org/job/PreCommit-HDFS-Build/10593/console |


This message was automatically generated.

> Fix some issue in DFSInputstream
> --------------------------------
>
>                 Key: HDFS-4273
>                 URL: https://issues.apache.org/jira/browse/HDFS-4273
>             Project: Hadoop HDFS
>          Issue Type: Bug
>    Affects Versions: 2.0.2-alpha
>            Reporter: Binglin Chang
>            Assignee: Binglin Chang
>            Priority: Minor
>         Attachments: HDFS-4273-v2.patch, HDFS-4273.patch, HDFS-4273.v3.patch, HDFS-4273.v4.patch, HDFS-4273.v5.patch, HDFS-4273.v6.patch, HDFS-4273.v7.patch, HDFS-4273.v8.patch, TestDFSInputStream.java
>
>
> Following issues in DFSInputStream are addressed in this jira:
> 1. read may not retry enough in some cases cause early failure
> Assume the following call logic
> {noformat} 
> readWithStrategy()
>   -> blockSeekTo()
>   -> readBuffer()
>      -> reader.doRead()
>      -> seekToNewSource() add currentNode to deadnode, wish to get a different datanode
>         -> blockSeekTo()
>            -> chooseDataNode()
>               -> block missing, clear deadNodes and pick the currentNode again
>         seekToNewSource() return false
>      readBuffer() re-throw the exception quit loop
> readWithStrategy() got the exception,  and may fail the read call before tried MaxBlockAcquireFailures.
> {noformat} 
> 2. In multi-threaded scenario(like hbase), DFSInputStream.failures has race condition, it is cleared to 0 when it is still used by other thread. So it is possible that  some read thread may never quit. Change failures to local variable solve this issue.
> 3. If local datanode is added to deadNodes, it will not be removed from deadNodes if DN is back alive. We need a way to remove local datanode from deadNodes when the local datanode is become live.


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