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https://issues.apache.org/jira/browse/SPARK-18981?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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roncenzhao updated SPARK-18981:
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    Attachment: job_hang.png

> The last job hung when speculation is on
> ----------------------------------------
>
>                 Key: SPARK-18981
>                 URL: https://issues.apache.org/jira/browse/SPARK-18981
>             Project: Spark
>          Issue Type: Bug
>          Components: Spark Core
>    Affects Versions: 2.0.2
>         Environment: spark2.0.2
> hadoop2.5.0
>            Reporter: roncenzhao
>            Priority: Critical
>         Attachments: job_hang.png
>
>
> CONF:
> spark.speculation   true
> spark.dynamicAllocation.minExecutors    0
> spark.executor.cores   4
> When I run the follow app, the bug will trigger.
> ```
> sc.runJob(job1)
> sleep(100s)
> sc.runJob(job2) // the job2 will hang and never be scheduled
> ```
> The triggering condition is described as follows:
> condition1: During the sleeping time, the executors will be released and the 
> # of the executor will be zero some seconds later. The #numExecutorsTarget in 
> 'ExecutorAllocationManager' will be 0.
> condition2: In 'ExecutorAllocationListener.onTaskEnd()', the numRunningTasks 
> will be negative during the ending of job1's tasks. 
> condition3: The job2 only hava one task.
> result:
> In the method 'ExecutorAllocationManager.updateAndSyncNumExecutorsTarget()', 
> we will calculate #maxNeeded in 'maxNumExecutorsNeeded()'. Obviously, 
> #numRunningOrPendingTasks will be negative and the #maxNeeded will be 0 or 
> negative. So the 'ExecutorAllocationManager' will not request container from 
> yarn. The app will hang.



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