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https://issues.apache.org/jira/browse/MAPREDUCE-1119?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12778288#action_12778288
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Vinod K V commented on MAPREDUCE-1119:
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The patch looks very clean now! Thanks! It is very close, I have only few
comments on the latest patch, most of them minor:
- Care explain the changes to {{src/c++/task-controller/main.c}} w.r.t
conf_dir_len? Both for my confirmation as well as for record's sake..
- Change c comments for {{kill_user_task()}} in
{{src/c++task-controller/task-controller.c}} mentioning that it can
terminate/kill or dump-stack?
- Now that the semantics have changed, I am not very sure we want to use the
same configuration property for sleeping after dump-stack. (Thinking aloud..)
Do we even need a sleep here? The signalling order is
SIGQUIT->SIGTERM->SIGKILL. Will signals be processed in the order of their
arrival? If so, then we will not another sleep. If not, we may need a sleep
here, but may or may not be driven by the same config item. What do you think?
- All the three newly added methods in {{JvmManager}} can be package-private
or private.
- ProcessTree.java:
-- Lot of refactoring. Nice!
-- The variables SIG* and SIG*_STR can all be private, so can
{{maybeSignalProcess()}} and {{maybeSignalProcessGroup()}} be.
- TestJobKillAndFail
-- Are we sure "PSPermGen" will always be there in the dump? Instead how
about passing our own {{TaskController}} that does custom actions in
{{TaskController.dumpStacks()}}, simplifying our verification that dump-stack
is indeed called?
-- The test now takes very long time. The test-time can be more than halved
if we set max-map-attempts to one in both the tests via
{{conf.setMaxMapAttempts(1);}}
- We need a similar test for {{LinuxTaskController}} to test stack-dump when
multiple users are involved. You can look at
{{TestLocalizationWithLinuxTaskController}} and/or
{{TestJobExecutionAsDifferentUser}} for inspiration.
> When tasks fail to report status, show tasks's stack dump before killing
> ------------------------------------------------------------------------
>
> Key: MAPREDUCE-1119
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1119
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: tasktracker
> Affects Versions: 0.22.0
> Reporter: Todd Lipcon
> Assignee: Aaron Kimball
> Attachments: MAPREDUCE-1119.2.patch, MAPREDUCE-1119.3.patch,
> MAPREDUCE-1119.4.patch, MAPREDUCE-1119.5.patch, MAPREDUCE-1119.patch
>
>
> When the TT kills tasks that haven't reported status, it should somehow
> gather a stack dump for the task. This could be done either by sending a
> SIGQUIT (so the dump ends up in stdout) or perhaps something like JDI to
> gather the stack directly from Java. This may be somewhat tricky since the
> child may be running as another user (so the SIGQUIT would have to go through
> LinuxTaskController). This feature would make debugging these kinds of
> failures much easier, especially if we could somehow get it into the
> TaskDiagnostic message
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