[ 
https://issues.apache.org/jira/browse/TEZ-2214?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14379375#comment-14379375
 ] 

Hadoop QA commented on TEZ-2214:
--------------------------------

{color:red}-1 overall{color}.  Here are the results of testing the latest 
attachment
  http://issues.apache.org/jira/secure/attachment/12707144/TEZ-2214.3.patch
  against master revision 60ddcba.

    {color:green}+1 @author{color}.  The patch does not contain any @author 
tags.

    {color:red}-1 tests included{color}.  The patch doesn't appear to include 
any new or modified tests.
                        Please justify why no new tests are needed for this 
patch.
                        Also please list what manual steps were performed to 
verify this patch.

    {color:green}+1 javac{color}.  The applied patch does not increase the 
total number of javac compiler warnings.

    {color:green}+1 javadoc{color}.  There were no new javadoc warning messages.

    {color:green}+1 findbugs{color}.  The patch does not introduce any new 
Findbugs (version 2.0.3) warnings.

    {color:green}+1 release audit{color}.  The applied patch does not increase 
the total number of release audit warnings.

    {color:green}+1 core tests{color}.  The patch passed unit tests in .

Test results: https://builds.apache.org/job/PreCommit-TEZ-Build/344//testReport/
Console output: https://builds.apache.org/job/PreCommit-TEZ-Build/344//console

This message is automatically generated.

> FetcherOrderedGrouped can get stuck indefinitely when MergeManager misses 
> memToDiskMerging
> ------------------------------------------------------------------------------------------
>
>                 Key: TEZ-2214
>                 URL: https://issues.apache.org/jira/browse/TEZ-2214
>             Project: Apache Tez
>          Issue Type: Bug
>            Reporter: Rajesh Balamohan
>            Assignee: Rajesh Balamohan
>         Attachments: TEZ-2214.1.patch, TEZ-2214.2.patch, TEZ-2214.3.patch
>
>
> Scenario:
> - commitMemory & usedMemory are beyond their allowed threshold.
> - InMemoryMerge kicks off and is in the process of flushing memory contents 
> to disk
> - As it progresses, it releases memory segments as well (but not yet over).
> - Fetchers who need memory < maxSingleShuffleLimit, get scheduled.
> - If fetchers are fast, this quickly adds up to commitMemory & usedMemory. 
> Since InMemoryMerge is already in progress, this wouldn't trigger another 
> merge().
> - Pretty soon all fetchers would be stalled and get into the following state.
> {noformat}
> Thread 9351: (state = BLOCKED)
>  - java.lang.Object.wait(long) @bci=0 (Compiled frame; information may be 
> imprecise)
>  - java.lang.Object.wait() @bci=2, line=502 (Compiled frame)
>  - 
> org.apache.tez.runtime.library.common.shuffle.orderedgrouped.MergeManager.waitForShuffleToMergeMemory()
>  @bci=17, line=337 (Interpreted frame)
>  - 
> org.apache.tez.runtime.library.common.shuffle.orderedgrouped.FetcherOrderedGrouped.run()
>  @bci=34, line=157 (Interpreted frame)
> {noformat}
> - Even if InMemoryMerger completes, "commitedMem & usedMem" are beyond their 
> threshold and no other fetcher threads (all are in stalled state) are there 
> to release memory. This causes fetchers to wait indefinitely.



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