Details
Critical Description
Recently we did some performance tests and found two NPE problems when calling rmContext.getRMApps().get(appId).get...
These NPE problems occasionally happened when doing performance tests with large number and fast-finished applications. We have checked other places which call rmContext.getRMApps().get(...), most of them have null check and some does not need (The process can guarantee that the return result will not be null).
To fix these problems, We can add a null check for application before getting attempt form it.
(1) NPE in RMContainerImpl$FinishedTransition#updateAttemptMetrics
java.lang.NullPointerException at org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainerImpl$FinishedTransition.updateAttemptMetrics(RMContainerImpl.java:742) at org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainerImpl$FinishedTransition.transition(RMContainerImpl.java:715) at org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainerImpl$FinishedTransition.transition(RMContainerImpl.java:699) at org.apache.hadoop.yarn.state.StateMachineFactory$SingleInternalArc.doTransition(StateMachineFactory.java:362) at org.apache.hadoop.yarn.state.StateMachineFactory.doTransition(StateMachineFactory.java:302) at org.apache.hadoop.yarn.state.StateMachineFactory.access$500(StateMachineFactory.java:46) at org.apache.hadoop.yarn.state.StateMachineFactory$InternalStateMachine.doTransition(StateMachineFactory.java:487) at org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainerImpl.handle(RMContainerImpl.java:482) at org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainerImpl.handle(RMContainerImpl.java:64) at org.apache.hadoop.yarn.server.resourcemanager.scheduler.common.fica.FiCaSchedulerApp.containerCompleted(FiCaSchedulerApp.java:195) at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.LeafQueue.completedContainer(LeafQueue.java:1793) at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.completedContainerInternal(CapacityScheduler.java:2624) at org.apache.hadoop.yarn.server.resourcemanager.scheduler.AbstractYarnScheduler.completedContainer(AbstractYarnScheduler.java:663) at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.doneApplicationAttempt(CapacityScheduler.java:1514) at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.handle(CapacityScheduler.java:2396) at org.apache.hadoop.yarn.sls.scheduler.SLSCapacityScheduler.handle(SLSCapacityScheduler.java:205) at org.apache.hadoop.yarn.sls.scheduler.SLSCapacityScheduler.handle(SLSCapacityScheduler.java:60) at org.apache.hadoop.yarn.event.EventDispatcher$EventProcessor.run(EventDispatcher.java:66) at java.lang.Thread.run(Thread.java:834)
This NPE looks like happen when node heartbeat delay and try to update attempt metrics for a non-exist app.
Reference code of RMContainerImpl$FinishedTransition#updateAttemptMetrics:
private static void updateAttemptMetrics(RMContainerImpl container) { Resource resource = container.getContainer().getResource(); RMAppAttempt rmAttempt = container.rmContext.getRMApps() .get(container.getApplicationAttemptId().getApplicationId()) .getCurrentAppAttempt(); if (rmAttempt != null) { //.... } }
(2) NPE in SchedulerApplicationAttempt#incNumAllocatedContainers
java.lang.NullPointerException
at org.apache.hadoop.yarn.server.resourcemanager.scheduler.SchedulerApplicationAttempt.incNumAllocatedContainers(SchedulerApplicationAttempt.java:1268)
at org.apache.hadoop.yarn.server.resourcemanager.scheduler.common.fica.FiCaSchedulerApp.apply(FiCaSchedulerApp.java:638)
at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.tryCommit(CapacityScheduler.java:3589)
at org.apache.hadoop.yarn.sls.scheduler.SLSCapacityScheduler.tryCommit(SLSCapacityScheduler.java:142)
at org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler$ResourceCommitterService.run(CapacityScheduler.java:962)
This NPE should happen when apply a outdated proposal for a non-existed application in rmContext.
Reference code:
RMAppAttempt attempt =
rmContext.getRMApps().get(attemptId.getApplicationId())
.getCurrentAppAttempt();
if (attempt != null) {
attempt.getRMAppAttemptMetrics().incNumAllocatedContainers(containerType,
requestType);
}