[
https://issues.apache.org/jira/browse/MAPREDUCE-4749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13488156#comment-13488156
]
Robert Joseph Evans commented on MAPREDUCE-4749:
------------------------------------------------
Ok I can see what happened here.
With MAPREDUCE-4088 the code in checkJobStatusAndWait changed from
{code}
if (rjob != null) {
synchronized (rjob) {
while (rjob.localizing) {
rjob.wait();
}
}
}
{code}
to
{code}
if (rjob != null) {
synchronized (rjob) {
rjob.wait(5000);
return !rjob.localizing;
}
}
{code}
The difference is that the while provided a short circuit that skipped the
waiting if localizing had already finished.
I think it would be preferable to add in the same sort of thing
{code}
if (rjob != null) {
synchronized (rjob) {
if (rjob.localizing) {
rjob.wait(5000);
}
return !rjob.localizing;
}
}
{code}
without a wait of some sort the loop that processes the actions could get stuck
in a tight loop waiting for localization to happen. Which works, but is not
ideal because it needlessly burns CPU cycles and can increase lock contention a
lot.
> Killing multiple attempts of a task taker longer as more attempts are killed
> ----------------------------------------------------------------------------
>
> Key: MAPREDUCE-4749
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4749
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Affects Versions: 1.1.0
> Reporter: Arpit Gupta
> Assignee: Arpit Gupta
> Attachments: MAPREDUCE-4749.branch-1.patch
>
>
> The following was noticed on a mr job running on hadoop 1.1.0
> 1. Start an mr job with 1 mapper
> 2. Wait for a min
> 3. Kill the first attempt of the mapper and then subsequently kill the other
> 3 attempts in order to fail the job
> The time taken to kill the task grew exponentially.
> 1st attempt was killed immediately.
> 2nd attempt took a little over a min
> 3rd attempt took approx. 20 mins
> 4th attempt took around 3 hrs.
> The command used to kill the attempt was "hadoop job -fail-task"
> Note that the command returned immediately as soon as the fail attempt was
> accepted but the time the attempt was actually killed was as stated above.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
