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Date: Wed, 18 May 2011 15:28:47 +0000 (UTC)
From: "ramkrishna.s.vasudevan (JIRA)" <jira@apache.org>
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Subject: [jira] [Updated] (HADOOP-7256) Resource leak during failure
 scenario of closing of resources.
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     [ https://issues.apache.org/jira/browse/HADOOP-7256?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

ramkrishna.s.vasudevan updated HADOOP-7256:
-------------------------------------------

    Fix Version/s: 0.23.0
     Hadoop Flags: [Incompatible change, Reviewed]  (was: [Incompatible change])
           Status: Patch Available  (was: Open)

> Resource leak during failure scenario of closing of resources. 
> ---------------------------------------------------------------
>
>                 Key: HADOOP-7256
>                 URL: https://issues.apache.org/jira/browse/HADOOP-7256
>             Project: Hadoop Common
>          Issue Type: Bug
>    Affects Versions: 0.21.0, 0.20.2
>            Reporter: ramkrishna.s.vasudevan
>            Priority: Minor
>             Fix For: 0.23.0
>
>         Attachments: HADOOP-7256-patch-1.patch
>
>   Original Estimate: 8h
>  Remaining Estimate: 8h
>
> Problem Statement:
> ===============
> There are chances of resource leak and stream not getting closed 
> Take the case when after copying data we try to close the Input and output stream followed by closing of the socket.
> Suppose an exception occurs while closing the input stream(due to runtime exception) then the subsequent operations of closing the output stream and socket may not happen and there is a chance of resource leak.
> Scenario 
> =======
> During long run of map reduce jobs, the copyFromLocalFile() api is getting called.
> Here we found some exceptions happening. As a result of this we found the lsof value raising leading to resource leak.
> Solution:
> =======
> While doing a close operation of any resource catch the RuntimeException also rather than catching the IOException alone.
> Additionally there are places where we try to close a resource in the catch block.
> If this close fails, we just throw and come out of the current flow.
> In order to avoid this, we can carry out the close operation in the finally block.
> Probable reasons for getting RunTimeExceptions:
> =====================================
> We may get runtime exception from customised hadoop streams like FSDataOutputStream.close() . So better to handle RunTimeExceptions also.
>  

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