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https://issues.apache.org/jira/browse/MAPREDUCE-2157?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12925151#action_12925151
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Joydeep Sen Sarma commented on MAPREDUCE-2157:
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see: https://issues.apache.org/bugzilla/show_bug.cgi?id=44157
with the patch for this - log4j is setting interrupted state for threads. i
think this bug and the comments suggest that there may be cases where
InterruptedException is still being propagated from log4j (which is actually
the more likely culprit for MAPREDUCE-2157). so it makes sense, as a
precaution, to check for shutdown conditions inside interruptedexception
handlers before exiting.
> tasklauncher threads in TaskTracker can die because of unexpected interrupts
> ----------------------------------------------------------------------------
>
> Key: MAPREDUCE-2157
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2157
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Reporter: Joydeep Sen Sarma
> Assignee: Joydeep Sen Sarma
> Priority: Critical
>
> taskLauncher thread exits on interruptedException and on Interrupt conditions
> without checking for any shutdown flag:
> while (!Thread.interrupted()) {
> ...
> } catch (InterruptedException e) {
> return; // ALL DONE
>
> }
> }
> If the interrupt happened because of reasons other than TaskTracker.close() -
> then the TaskTracker will look functional - but will not be able to schedule
> tasks anymore. worse - some tasks (that are in the launch queue) will hang
> indefinitely un UNASSIGNED state (the JobTracker will not even time them
> out). We have seen this cause jobs to hang indefinitely.
> It seems that the interrupted condition can be set by log4j (of which there
> are many calls inside TaskLauncher). See or instance:
> http://logging.apache.org/log4j/1.2/xref/org/apache/log4j/AsyncAppender.html
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