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https://issues.apache.org/jira/browse/MAPREDUCE-5966?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Anubhav Dhoot updated MAPREDUCE-5966:
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Attachment: MAPREDUCE-5966.002.patch
Attaching patch that addresses feedback
> 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
> Attachments: MAPREDUCE-5966.001.patch, MAPREDUCE-5966.002.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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