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https://issues.apache.org/jira/browse/YARN-1458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14103678#comment-14103678
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zhihai xu commented on YARN-1458:
---------------------------------

The patch didn't consider type conversion from double to integer in 
computeShare will lose precision. So "break when zero" will cause all  
Schedulable's FairShare to be zero if all Schedulable's Weight and MinShare are 
less than 1. In the unit test, the queues' Weight are 0.25 and 0.75, the 
queues' MinShare are Resources.none().
I will create a new patch.

> In Fair Scheduler, size based weight can cause update thread to hold lock 
> indefinitely
> --------------------------------------------------------------------------------------
>
>                 Key: YARN-1458
>                 URL: https://issues.apache.org/jira/browse/YARN-1458
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: scheduler
>    Affects Versions: 2.2.0
>         Environment: Centos 2.6.18-238.19.1.el5 X86_64
> hadoop2.2.0
>            Reporter: qingwu.fu
>            Assignee: zhihai xu
>              Labels: patch
>             Fix For: 2.2.1
>
>         Attachments: YARN-1458.patch
>
>   Original Estimate: 408h
>  Remaining Estimate: 408h
>
> The ResourceManager$SchedulerEventDispatcher$EventProcessor blocked when 
> clients submit lots jobs, it is not easy to reapear. We run the test cluster 
> for days to reapear it. The output of  jstack command on resourcemanager pid:
> {code}
>  "ResourceManager Event Processor" prio=10 tid=0x00002aaab0c5f000 nid=0x5dd3 
> waiting for monitor entry [0x0000000043aa9000]
>    java.lang.Thread.State: BLOCKED (on object monitor)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler.removeApplication(FairScheduler.java:671)
>         - waiting to lock <0x000000070026b6e0> (a 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler.handle(FairScheduler.java:1023)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler.handle(FairScheduler.java:112)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.ResourceManager$SchedulerEventDispatcher$EventProcessor.run(ResourceManager.java:440)
>         at java.lang.Thread.run(Thread.java:744)
> ……
> "FairSchedulerUpdateThread" daemon prio=10 tid=0x00002aaab0a2c800 nid=0x5dc8 
> runnable [0x00000000433a2000]
>    java.lang.Thread.State: RUNNABLE
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler.getAppWeight(FairScheduler.java:545)
>         - locked <0x000000070026b6e0> (a 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.AppSchedulable.getWeights(AppSchedulable.java:129)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.policies.ComputeFairShares.computeShare(ComputeFairShares.java:143)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.policies.ComputeFairShares.resourceUsedWithWeightToResourceRatio(ComputeFairShares.java:131)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.policies.ComputeFairShares.computeShares(ComputeFairShares.java:102)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.policies.FairSharePolicy.computeShares(FairSharePolicy.java:119)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FSLeafQueue.recomputeShares(FSLeafQueue.java:100)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FSParentQueue.recomputeShares(FSParentQueue.java:62)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler.update(FairScheduler.java:282)
>         - locked <0x000000070026b6e0> (a 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler$UpdateThread.run(FairScheduler.java:255)
>         at java.lang.Thread.run(Thread.java:744)
> {code}



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