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https://issues.apache.org/jira/browse/MAPREDUCE-2116?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Arun C Murthy updated MAPREDUCE-2116:
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Status: Open (was: Patch Available)
Sorry to come in late, the patch has gone stale. Can you please rebase? Thanks.
Given this is not an issue with MRv2 should we still commit this? I'm happy to,
but not sure it's useful. Thanks.
> optimize getTasksToKill to reduce JobTracker contention
> -------------------------------------------------------
>
> Key: MAPREDUCE-2116
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2116
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: jobtracker
> Reporter: Joydeep Sen Sarma
> Assignee: Joydeep Sen Sarma
> Attachments: 2116.1.patch, 2116.2.patch, 2116.3.patch, 2116.4.patch,
> 2116.5.patch, getTaskToKill.JPG
>
>
> getTasksToKill shows up as one of the top routines holding the JT lock.
> Specifically, the translation from attemptid to tip is very expensive:
> at java.util.TreeMap.getEntry(TreeMap.java:328)
> at java.util.TreeMap.get(TreeMap.java:255)
> at
> org.apache.hadoop.mapred.TaskInProgress.shouldClose(TaskInProgress.java:500)
> at
> org.apache.hadoop.mapred.JobTracker.getTasksToKill(JobTracker.java:3464)
> locked <0x00002aab6ebb6640> (a org.apache.hadoop.mapred.JobTracker)
> at org.apache.hadoop.mapred.JobTracker.heartbeat(JobTracker.java:3181)
> this seems like an avoidable expense since the tip for a given attempt is
> fixed (and one should not need a map lookup to find the association). on a
> different note - not clear to me why TreeMaps are in use here (i didn't find
> any iteration over these maps). any background info on why things are
> arranged the way they are would be useful.
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