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https://issues.apache.org/jira/browse/HADOOP-3120?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12583155#action_12583155
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Pete Wyckoff commented on HADOOP-3120:
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I am setting it up on a non-hadoop test server, just to ensure it operates the
way I think it should. You are right, if we went from 10 microseconds/call to
something more like ~0.5-1 microsecond that should probably do it -- The 10
microseconds is measured from a call to LOG.info with a couple of strings and 2
ints to format (standalone program with idle disk and about a million calls).
The 0.5 is the same call with info logging disabled and just guestimating the
overhead of the call to AsyncAppender. Probably can have #s on asyncappender
performance maybe early next week.
-- pete
> Large #of tasks failing at one time can effectively hang the jobtracker
> ------------------------------------------------------------------------
>
> Key: HADOOP-3120
> URL: https://issues.apache.org/jira/browse/HADOOP-3120
> Project: Hadoop Core
> Issue Type: Bug
> Environment: Linux/Hadoop-15.3
> Reporter: Pete Wyckoff
> Priority: Minor
>
> We think that JobTracker.removeMarkedTaks does so much logging when this
> happens (ie logging thousands of failed taks per cycle) that nothing else can
> go on (since it's called from a synchronized method) and thus by the next
> cycle, the next waves of jobs have failed and we again have 10s of thousands
> of failures to log and on and on.
> At least, the above is what we observed - just a continual printing of those
> failures and nothing else happening on and on. Of course the original jobs
> may have ultimately failed but new jobs come in to perpetuate the problem.
> This has happened to us a number of times and since we commented out the
> log.info in that method we haven't had any problems. Although thousands and
> thousands of task failures are hopefully not that common.
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