[jira] [Created] (YARN-8737) Race condition in ParentQueue when reinitializing and sorting child queues in the meanwhile

["Tao Yang (JIRA)" <ji...@apache.org>]

Tao Yang created YARN-8737:
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             Summary: Race condition in ParentQueue when reinitializing and sorting child queues in the meanwhile
                 Key: YARN-8737
                 URL: https://issues.apache.org/jira/browse/YARN-8737
             Project: Hadoop YARN
          Issue Type: Bug
          Components: capacityscheduler
    Affects Versions: 3.2.0
            Reporter: Tao Yang
            Assignee: Tao Yang


Administrator raised a update for queues through REST API, in RM parent queue is refreshing child queues through calling ParentQueue#reinitialize, meanwhile, async-schedule threads is sorting child queues when calling ParentQueue#sortAndGetChildrenAllocationIterator. Race condition may happen and throw exception as follow because TimSort does not handle the concurrent modification of objects it is sorting:
{noformat}
java.lang.IllegalArgumentException: Comparison method violates its general contract!
        at java.util.TimSort.mergeHi(TimSort.java:899)
        at java.util.TimSort.mergeAt(TimSort.java:516)
        at java.util.TimSort.mergeCollapse(TimSort.java:441)
        at java.util.TimSort.sort(TimSort.java:245)
        at java.util.Arrays.sort(Arrays.java:1512)
        at java.util.ArrayList.sort(ArrayList.java:1454)
        at java.util.Collections.sort(Collections.java:175)
        at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.policy.PriorityUtilizationQueueOrderingPolicy.getAssignmentIterator(PriorityUtilizationQueueOrderingPolicy.java:291)
        at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.ParentQueue.sortAndGetChildrenAllocationIterator(ParentQueue.java:804)
        at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.ParentQueue.assignContainersToChildQueues(ParentQueue.java:817)
        at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.ParentQueue.assignContainers(ParentQueue.java:636)
        at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.allocateOrReserveNewContainers(CapacityScheduler.java:2494)
        at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.allocateOrReserveNewContainers(CapacityScheduler.java:2431)
        at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.allocateContainersOnMultiNodes(CapacityScheduler.java:2588)
        at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.allocateContainersToNode(CapacityScheduler.java:2676)
        at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.scheduleBasedOnNodeLabels(CapacityScheduler.java:927)
        at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler$AsyncScheduleThread.run(CapacityScheduler.java:962)
{noformat}

I think we can add read-lock for ParentQueue#sortAndGetChildrenAllocationIterator to solve this problem, the write-lock will be hold when updating child queues in ParentQueue#reinitialize.



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