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https://issues.apache.org/jira/browse/YARN-10178?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17273944#comment-17273944
 ] 

Wangda Tan commented on YARN-10178:
-----------------------------------

[~zhuqi], [~bteke], I'm wondering if it is the right fix, now we initialize 
PriorityQueueResourcesForSorting during compare(). However, compare will be 
called multiple times during one sorting call. It is still possible we can get 
an inconsistent result like before. 

To me the right fix should be done inside 
PriorityUtilizationQueueOrderingPolicy#getAssignmentIterator:  

We should take snapshots of ParentQueue's PriorityQueueResourcesForSorting 
first, and then sort PriorityQueueResourcesForSorting. (We may need to add a 
reference to ParentQueue from PriorityQueueResourcesForSorting).

And can we add tests to prevent side effect/regression?

> Global Scheduler async thread crash caused by 'Comparison method violates its 
> general contract'
> -----------------------------------------------------------------------------------------------
>
>                 Key: YARN-10178
>                 URL: https://issues.apache.org/jira/browse/YARN-10178
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: capacity scheduler
>    Affects Versions: 3.2.1
>            Reporter: tuyu
>            Assignee: zhuqi
>            Priority: Major
>         Attachments: YARN-10178.001.patch, YARN-10178.002.patch
>
>
> Global Scheduler Async Thread crash stack
> {code:java}
> ERROR org.apache.hadoop.yarn.server.resourcemanager.ResourceManager: Received 
> RMFatalEvent of type CRITICAL_THREAD_CRASH, caused by a critical thread, 
> Thread-6066574, that exited unexpectedly: 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.mergeForceCollapse(TimSort.java:457)
>         at java.util.TimSort.sort(TimSort.java:254)
>         at java.util.Arrays.sort(Arrays.java:1512)
>         at java.util.ArrayList.sort(ArrayList.java:1462)
>         at java.util.Collections.sort(Collections.java:177)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.policy.PriorityUtilizationQueueOrderingPolicy.getAssignmentIterator(PriorityUtilizationQueueOrderingPolicy.java:221)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.ParentQueue.sortAndGetChildrenAllocationIterator(ParentQueue.java:777)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.ParentQueue.assignContainersToChildQueues(ParentQueue.java:791)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.ParentQueue.assignContainers(ParentQueue.java:623)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.allocateOrReserveNewContainers(CapacityScheduler.java:1635)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.allocateContainerOnSingleNode(CapacityScheduler.java:1629)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.allocateContainersToNode(CapacityScheduler.java:1732)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.allocateContainersToNode(CapacityScheduler.java:1481)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.schedule(CapacityScheduler.java:569)
>         at 
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler$AsyncScheduleThread.run(CapacityScheduler.java:616)
> {code}
> JAVA 8 Arrays.sort default use timsort algo, and timsort has  few require 
> {code:java}
> 1.x.compareTo(y) != y.compareTo(x)
> 2.x>y,y>z --> x > z
> 3.x=y, x.compareTo(z) == y.compareTo(z)
> {code}
> if not Arrays paramters not satify this require,TimSort will throw 
> 'java.lang.IllegalArgumentException'
> look at PriorityUtilizationQueueOrderingPolicy.compare function,we will know 
> Capacity Scheduler use this these queue resource usage to compare
> {code:java}
> AbsoluteUsedCapacity
> UsedCapacity
> ConfiguredMinResource
> AbsoluteCapacity
> {code}
> In Capacity Scheduler Global Scheduler AsyncThread use 
> PriorityUtilizationQueueOrderingPolicy function to choose queue to assign 
> container,and construct a CSAssignment struct, and use 
> submitResourceCommitRequest function add CSAssignment to backlogs
> ResourceCommitterService  will tryCommit this CSAssignment,look tryCommit 
> function,there will update queue resource usage
> {code:java}
> public boolean tryCommit(Resource cluster, ResourceCommitRequest r,
>     boolean updatePending) {
>   long commitStart = System.nanoTime();
>   ResourceCommitRequest<FiCaSchedulerApp, FiCaSchedulerNode> request =
>       (ResourceCommitRequest<FiCaSchedulerApp, FiCaSchedulerNode>) r;
>  
>   ...
>   boolean isSuccess = false;
>   if (attemptId != null) {
>     FiCaSchedulerApp app = getApplicationAttempt(attemptId);
>     // Required sanity check for attemptId - when async-scheduling enabled,
>     // proposal might be outdated if AM failover just finished
>     // and proposal queue was not be consumed in time
>     if (app != null && attemptId.equals(app.getApplicationAttemptId())) {
>       if (app.accept(cluster, request, updatePending)
>           && app.apply(cluster, request, updatePending)) { // apply this 
> resource
>         ...
>         }
>     }
>   }
>   return isSuccess;
> }
> }
> {code}
> {code:java}
> public boolean apply(Resource cluster, ResourceCommitRequest<FiCaSchedulerApp,
>     FiCaSchedulerNode> request, boolean updatePending) {
> ...
>     if (!reReservation) {
>         getCSLeafQueue().apply(cluster, request); 
>     }
> ...
> }
> {code}
> LeafQueue.apply invok allocateResource
> {code:java}
> void allocateResource(Resource clusterResource,
>     Resource resource, String nodePartition) {
>   try {
>     writeLock.lock(); // only lock leaf queue lock
>     queueUsage.incUsed(nodePartition, resource);
>  
>     ++numContainers;
>  
>     CSQueueUtils.updateQueueStatistics(resourceCalculator, clusterResource,
>         this, labelManager, nodePartition); // there will update queue 
> statistics
>   } finally {
>     writeLock.unlock();
>   }
> }
> {code}
> we found ResourceCommitterService will only lock leaf queue to update queue 
> statistics, but AsyncThread use sortAndGetChildrenAllocationIterator only 
> lock queue root queue lock
> {code:java}
> ParentQueue.java
> private Iterator<CSQueue> sortAndGetChildrenAllocationIterator(
>       String partition) {
>     try {
>       readLock.lock();
>       return queueOrderingPolicy.getAssignmentIterator(partition);
>     } finally {
>       readLock.unlock();
>     }
>   }
> {code}
> so if multi async thread compare queue usage statistics and 
> ResourceCommitterService apply leaf queue change statistics concurrent, will 
> break TimSort algo required, and cause thread crash



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