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Posted to common-dev@hadoop.apache.org by "Amar Kamat (JIRA)" <ji...@apache.org> on 2009/01/02 13:19:44 UTC

[jira] Commented: (HADOOP-4766) Hadoop performance degrades significantly as more and more jobs complete

    [ https://issues.apache.org/jira/browse/HADOOP-4766?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12660308#action_12660308 ] 

Amar Kamat commented on HADOOP-4766:
------------------------------------

Ran 14 jobs back to back each of 100,000 tasks and the runtimes are as follows
||no||job-runtime||
|1|17mins|
|2|17mins|
|3|17mins|
|4|18mins|
|5|17mins|
|6|17mins|
|7|17mins|
|8|17mins|
|9|17mins|
|10|17mins|
|11|17mins|
|12|17mins|
|13|17mins|
|14|17mins|

It shows that there is no performance degradation.

> Hadoop performance degrades significantly as more and more jobs complete
> ------------------------------------------------------------------------
>
>                 Key: HADOOP-4766
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4766
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>    Affects Versions: 0.18.2, 0.19.0
>            Reporter: Runping Qi
>            Assignee: Amar Kamat
>            Priority: Blocker
>             Fix For: 0.18.3, 0.19.1, 0.20.0
>
>         Attachments: HADOOP-4766-v1.patch, HADOOP-4766-v2.4.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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