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https://issues.apache.org/jira/browse/MAPREDUCE-177?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13185376#comment-13185376
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Evan Pollan commented on MAPREDUCE-177:
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This defect affects me after just 10-15 iterations of a daily job that has on
the order to 10K mappers and a thousand or so reducers. This is cropping up
using 0.20.2 (from CDH2U3). This seems like a pretty serious problem affecting
the longevity of the job tracker. Is there a reason a fix hasn't been committed
and released?
> Hadoop performance degrades significantly as more and more jobs complete
> ------------------------------------------------------------------------
>
> Key: MAPREDUCE-177
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-177
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Reporter: Runping Qi
> Assignee: Ioannis Koltsidas
> Priority: Critical
> Attachments: HADOOP-4766-v1.patch, HADOOP-4766-v2.10.patch,
> HADOOP-4766-v2.4.patch, HADOOP-4766-v2.6.patch, HADOOP-4766-v2.7-0.18.patch,
> HADOOP-4766-v2.7-0.19.patch, HADOOP-4766-v2.7.patch,
> HADOOP-4766-v2.8-0.18.patch, HADOOP-4766-v2.8-0.19.patch,
> HADOOP-4766-v2.8.patch, HADOOP-4766-v3.4-0.19.patch, map_scheduling_rate.txt
>
>
> When I ran the gridmix 2 benchmark load on a fresh cluster of 500 nodes with
> hadoop trunk,
> the gridmix load, consisting of 202 map/reduce jobs of various sizes,
> completed in 32 minutes.
> Then I ran the same set of the jobs on the same cluster, yhey completed in 43
> minutes.
> When I ran them the third times, it took (almost) forever --- the job tracker
> became non-responsive.
> The job tracker's heap size was set to 2GB.
> The cluster is configured to keep up to 500 jobs in memory.
> The job tracker kept one cpu busy all the time. Look like it was due to GC.
> I believe the release 0.18/0.19 have the similar behavior.
> I believe 0.18 and 0.18 also have the similar behavior.
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