[jira] Commented: (HADOOP-3089) streaming should accept stderr from task before first key arrives

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

    [ https://issues.apache.org/jira/browse/HADOOP-3089?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12582101#action_12582101 ] 

Hadoop QA commented on HADOOP-3089:
-----------------------------------

+1 overall.  Here are the results of testing the latest attachment 
http://issues.apache.org/jira/secure/attachment/12378598/patch-stderr-3089.txt
against trunk revision 619744.

    @author +1.  The patch does not contain any @author tags.

    tests included +1.  The patch appears to include 6 new or modified tests.

    javadoc +1.  The javadoc tool did not generate any warning messages.

    javac +1.  The applied patch does not generate any new javac compiler warnings.

    release audit +1.  The applied patch does not generate any new release audit warnings.

    findbugs +1.  The patch does not introduce any new Findbugs warnings.

    core tests +1.  The patch passed core unit tests.

    contrib tests +1.  The patch passed contrib unit tests.

Test results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2056/testReport/
Findbugs warnings: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2056/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Checkstyle results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2056/artifact/trunk/build/test/checkstyle-errors.html
Console output: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2056/console

This message is automatically generated.

> streaming should accept stderr from task before first key arrives
> -----------------------------------------------------------------
>
>                 Key: HADOOP-3089
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3089
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: contrib/streaming
>    Affects Versions: 0.14.0, 0.14.1, 0.14.2, 0.14.3, 0.14.4, 0.15.0, 0.15.1, 0.15.2, 0.15.3, 0.16.0, 0.16.1
>            Reporter: Rick Cox
>            Assignee: Rick Cox
>             Fix For: 0.17.0
>
>         Attachments: patch-stderr-3089.txt
>
>
> Stderr output from a streaming task is not collected until the {{MRErrorThread}} is started by {{PipeMapRed.startOutputThreads()}}, which is done on the first call to {{map()}} or {{reduce()}}.
> This makes it difficult to debug failures in starting up the task process. It can also lead to deadlock when a task receives no input keys but produces significant stderr output: the process will block on writing to stderr, while streaming will block waiting for the process to exit.
> We should start the {{MRErrorThread}} when the process is forked, and then add the {{reporter}} later to enable stderr output serve as a keep-alive.

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