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From "Hong Zhiguo (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (YARN-1889) avoid creating new objects on each fair scheduler call to AppSchedulable comparator
Date Fri, 28 Mar 2014 09:30:19 GMT

     [ https://issues.apache.org/jira/browse/YARN-1889?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Hong Zhiguo updated YARN-1889:
------------------------------

    Attachment: YARN-1889.patch

> avoid creating new objects on each fair scheduler call to AppSchedulable comparator
> -----------------------------------------------------------------------------------
>
>                 Key: YARN-1889
>                 URL: https://issues.apache.org/jira/browse/YARN-1889
>             Project: Hadoop YARN
>          Issue Type: Improvement
>          Components: scheduler
>            Reporter: Hong Zhiguo
>            Priority: Minor
>         Attachments: YARN-1889.patch
>
>
> In fair scheduler, in each scheduling attempt, a full sort is
> performed on List of AppSchedulable, which invokes Comparator.compare
> method many times. Both FairShareComparator and DRFComparator call
> AppSchedulable.getWeights, and AppSchedulable.getPriority.
> A new ResourceWeights object is allocated on each call of getWeights,
> and the same for getPriority. This introduces a lot of pressure to
> GC because these methods are called very very frequently.
> Below test case shows improvement on performance and GC behaviour. The results show that
the GC pressure during processing NodeUpdate is recuded half by this patch.
> The code to show the improvement: (Add it to TestFairScheduler.java)
> import java.lang.management.GarbageCollectorMXBean;
> import java.lang.management.ManagementFactory;
>   public void printGCStats() {
>     long totalGarbageCollections = 0;
>     long garbageCollectionTime = 0;
>     for(GarbageCollectorMXBean gc :
>       ManagementFactory.getGarbageCollectorMXBeans()) {
>       long count = gc.getCollectionCount();
>       if(count >= 0) {
>         totalGarbageCollections += count;
>       }
>       long time = gc.getCollectionTime();
>       if(time >= 0) {
>         garbageCollectionTime += time;
>       }
>     }
>     System.out.println("Total Garbage Collections: "
>         + totalGarbageCollections);
>     System.out.println("Total Garbage Collection Time (ms): "
>         + garbageCollectionTime);
>   }
>   @Test
>   public void testImpactOnGC() throws Exception {
>     scheduler.reinitialize(conf, resourceManager.getRMContext());
>     // Add nodes
>     int numNode = 10000;
>     for (int i = 0; i < numNode; ++i) {
>         String host = String.format("192.1.%d.%d", i/256, i%256);
>         RMNode node =
>             MockNodes.newNodeInfo(1, Resources.createResource(1024 * 64), i, host);
>         NodeAddedSchedulerEvent nodeEvent = new NodeAddedSchedulerEvent(node);
>         scheduler.handle(nodeEvent);
>         assertEquals(1024 * 64 * (i+1), scheduler.getClusterCapacity().getMemory());
>     }
>     assertEquals(numNode, scheduler.getNumClusterNodes());
>     assertEquals(1024 * 64 * numNode, scheduler.getClusterCapacity().getMemory());
>     // add apps, each app has 100 containers.
>     int minReqSize =
>         FairSchedulerConfiguration.DEFAULT_RM_SCHEDULER_INCREMENT_ALLOCATION_MB;
>     int numApp = 8000;
>     int priority = 1;
>     for (int i = 1; i < numApp + 1; ++i) {
>         ApplicationAttemptId attemptId = createAppAttemptId(i, 1);
>         AppAddedSchedulerEvent appAddedEvent = new AppAddedSchedulerEvent(
>                         attemptId.getApplicationId(), "queue1", "user1");
>         scheduler.handle(appAddedEvent);
>         AppAttemptAddedSchedulerEvent attemptAddedEvent =
>             new AppAttemptAddedSchedulerEvent(attemptId, false);
>         scheduler.handle(attemptAddedEvent);
>         createSchedulingRequestExistingApplication(minReqSize * 2, 1, priority, attemptId);
>     }
>     scheduler.update();
>     assertEquals(numApp, scheduler.getQueueManager().getLeafQueue("queue1", true)
>         .getRunnableAppSchedulables().size());
>     System.out.println("GC stats before NodeUpdate processing:");
>     printGCStats();
>     int hb_num = 5000;
>     long start = System.nanoTime();
>     for (int i = 0; i < hb_num; ++i) {
>       String host = String.format("192.1.%d.%d", i/256, i%256);
>       RMNode node =
>           MockNodes.newNodeInfo(1, Resources.createResource(1024 * 64), 5000, host);
>       NodeUpdateSchedulerEvent nodeEvent = new NodeUpdateSchedulerEvent(node);
>       scheduler.handle(nodeEvent);
>     }
>     long end = System.nanoTime();
>     System.out.printf("processing time for a NodeUpdate in average: %d us\n",
>                 (end - start)/(hb_num * 1000));
>     System.out.println("GC stats after NodeUpdate processing:");
>     printGCStats();
>   }



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