[jira] [Comment Edited] (MAPREDUCE-5966) MR1 FairScheduler use of custom weight adjuster is not thread safe for comparisons

["Karthik Kambatla (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MAPREDUCE-5966?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14075480#comment-14075480 ] 

Karthik Kambatla edited comment on MAPREDUCE-5966 at 7/26/14 7:58 PM:
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Thanks for the patch, Anubhav. Just committed to branch-1.


was (Author: kkambatl):
Thanks for the patch, Anubhav. Just committed to trunk and branch-2. 

> MR1 FairScheduler use of custom weight adjuster is not thread safe for comparisons
> ----------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-5966
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-5966
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: scheduler
>    Affects Versions: 1.2.1
>            Reporter: Anubhav Dhoot
>            Assignee: Anubhav Dhoot
>             Fix For: 1.3.0
>
>         Attachments: MAPREDUCE-5966.001.patch, MAPREDUCE-5966.002.patch, mr-5966-3.patch
>
>
> When comparing JobSchedulables one of the factors is the weight. If someone uses a custom weight adjuster, that may be called multiple times during a sort causing different values to return. That causes a failure in sorting because the weight may change during the sort.
> This reproes as 
> {code}
> java.io.IOException: java.lang.IllegalArgumentException: Comparison method violates its general contract!
> at java.util.TimSort.mergeHi(TimSort.java:868)
> at java.util.TimSort.mergeAt(TimSort.java:485)
> at java.util.TimSort.mergeCollapse(TimSort.java:410)
> at java.util.TimSort.sort(TimSort.java:214)
> at java.util.TimSort.sort(TimSort.java:173)
> at java.util.Arrays.sort(Arrays.java:659)
> at java.util.Collections.sort(Collections.java:217)
> at org.apache.hadoop.mapred.PoolSchedulable.assignTask(PoolSchedulable.java:163)
> at org.apache.hadoop.mapred.FairScheduler.assignTasks(FairScheduler.java:499)
> at org.apache.hadoop.mapred.JobTracker.heartbeat(JobTracker.java:2961)
> {code}



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