You are viewing a plain text version of this content. The canonical link for it is here.
Posted to mapreduce-issues@hadoop.apache.org by "Kang Xiao (JIRA)" <ji...@apache.org> on 2011/02/16 06:37:58 UTC
[jira] Commented: (MAPREDUCE-2116) optimize getTasksToKill to
reduce JobTracker contention
[ https://issues.apache.org/jira/browse/MAPREDUCE-2116?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12995176#comment-12995176 ]
Kang Xiao commented on MAPREDUCE-2116:
--------------------------------------
I am sorry for late response. A patch attached for the suggestion. It just uses the same as getTasksToSave() to iterator only on running tasks on the tasktracker.
> 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, 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.
--
This message is automatically generated by JIRA.
-
For more information on JIRA, see: http://www.atlassian.com/software/jira