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https://issues.apache.org/jira/browse/YARN-1458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13836326#comment-13836326
 ] 

Sandy Ryza commented on YARN-1458:
----------------------------------

Cool, in that case I think I understand the problem.
{code}
      if (sizeBasedWeight) {
        // Set weight based on current memory demand
        weight = Math.log1p(app.getDemand().getMemory()) / Math.log(2);
      }
{code}
If size based weight is turned on, the weight is calculated as log(1 + demand), 
which will be 0 if demand is 0.  An app that has not yet submitted resource 
requests or otherwise has 0 demand will thus cause the weight to be 0, which, 
as discussed above, causes the update thread to loop indefinitely.

The best solution is probably to handle 0 values of 
resourceUsedWithWeightToResourceRatio in ComputeFairShares#computeShares.  If 
it returns 0 we should just set the fair shares of all the considered 
schedulables to 0.

If one of you who uncovered this wants to post a patch, I can review it.  
Otherwise I'll post a patch sometime later this week.

> hadoop2.2.0 fairscheduler ResourceManager Event Processor thread blocked
> ------------------------------------------------------------------------
>
>                 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
>              Labels: 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:
>  "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)



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