[jira] [Commented] (TEZ-3972) Tez DAG can hang when a single task fails to fetch

["TezQA (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TEZ-3972?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16549965#comment-16549965 ] 

TezQA commented on TEZ-3972:
----------------------------

{color:red}-1 overall{color}.  Here are the results of testing the latest attachment
  http://issues.apache.org/jira/secure/attachment/12932315/TEZ-3972.001.patch
  against master revision 7e397b4.

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

    {color:green}+1 tests included{color}.  The patch appears to include 1 new or modified test files.

      {color:red}-1 javac{color}.  The applied patch generated 178 javac compiler warnings (more than the master's current 177 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 3.0.1) 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/2870//testReport/
Javac warnings: https://builds.apache.org/job/PreCommit-TEZ-Build/2870//artifact/patchprocess/diffJavacWarnings.txt
Console output: https://builds.apache.org/job/PreCommit-TEZ-Build/2870//console

This message is automatically generated.


> Tez DAG can hang when a single task fails to fetch
> --------------------------------------------------
>
>                 Key: TEZ-3972
>                 URL: https://issues.apache.org/jira/browse/TEZ-3972
>             Project: Apache Tez
>          Issue Type: Bug
>    Affects Versions: 0.9.1
>            Reporter: Kuhu Shukla
>            Assignee: Kuhu Shukla
>            Priority: Major
>         Attachments: TEZ-3972.001.patch
>
>
> Description of the hung DAG:
> A DAG with 2 vertices. {{Map}} Vertex has 22k maps, downstream vertex {{Reduce}} has 1009 tasks. All tasks succeed but one, which hangs. This one task (attempt) is doing a local fetch from a node that (now) has a bad disk. It fails to fetch and reports to the AM for the offending input attempt identifiers. However the AM does not schedule a re-run as {{uniquefailedOutputReports}} size is 1 (since only this task attempt failed to fetch) and failure fraction is not met. The denominator for this fraction is the total number of tasks. That causes the re-run to never occur. This JIRA tracks the AM side of the change to alleviate this problem.



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