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YARN-11732. Fix potential NPE when calling SchedulerNode#reservedContainer for CapacityScheduler #7065

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Merged
merged 1 commit into from
Oct 16, 2024
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YARN-11732. Fix potential NPE when calling SchedulerNode#reservedContainer for CapacityScheduler #7065

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3 changes: 3 additions & 0 deletions ...oop/yarn/server/resourcemanager/monitor/capacity/ReservedContainerCandidatesSelector.java
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Expand Up @@ -170,6 +170,9 @@ private NodeForPreemption getPreemptionCandidatesOnNode(
Map<ApplicationAttemptId, Set<RMContainer>> selectedCandidates,
Resource totalPreemptionAllowed, boolean readOnly) {
RMContainer reservedContainer = node.getReservedContainer();
if (reservedContainer == null) {
return null;
}
Resource available = Resources.clone(node.getUnallocatedResource());
Resource totalSelected = Resources.createResource(0);
List<RMContainer> sortedRunningContainers =
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5 changes: 2 additions & 3 deletions ...n/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/AbstractYarnScheduler.java
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Expand Up @@ -757,10 +757,9 @@ private void completeOustandingUpdatesWhichAreReserved(
RMContainer rmContainer, ContainerStatus containerStatus,
RMContainerEventType event) {
N schedulerNode = getSchedulerNode(rmContainer.getNodeId());
if (schedulerNode != null &&
schedulerNode.getReservedContainer() != null) {
if (schedulerNode != null) {
RMContainer resContainer = schedulerNode.getReservedContainer();
if (resContainer.getReservedSchedulerKey() != null) {
if (resContainer != null && resContainer.getReservedSchedulerKey() != null) {
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It is recommended to add a try catch module. I have made this change in the production environment before, but it still reports a null pointer.

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@TaoYang526 TaoYang526 Sep 29, 2024 •
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Thanks @zeekling for the review.
I'm not sure why your environment still reported NPE after changing like that, resContainer.getReservedSchedulerKey() won't throw NPE any more with the previous not-null check: if resContainer is null. Could you please attach some details of the NPE and your changes?
For this change, I think NPE should be fixed instead of be caught in general.

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I modified like your change.

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I can't find any chance to reproduce the NPE, could you please explain in which case NPE can be thrown again? If we can locate that risk point, I would like to fix it instead of catching it in try block. Thanks.

ContainerId containerToUpdate = resContainer
.getReservedSchedulerKey().getContainerToUpdate();
if (containerToUpdate != null &&
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5 changes: 3 additions & 2 deletions ...p/yarn/server/resourcemanager/scheduler/capacity/allocator/RegularContainerAllocator.java
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Expand Up @@ -858,12 +858,13 @@ private ContainerAllocation allocate(Resource clusterResource,
FiCaSchedulerNode node = iter.next();

// Do not schedule if there are any reservations to fulfill on the node
RMContainer nodeReservedContainer = node.getReservedContainer();
if (iter.hasNext() &&
node.getReservedContainer() != null &&
nodeReservedContainer != null &&
isSkipAllocateOnNodesWithReservedContainer()) {
LOG.debug("Skipping scheduling on node {} since it has already been"
+ " reserved by {}", node.getNodeID(),
node.getReservedContainer().getContainerId());
nodeReservedContainer.getContainerId());
ActivitiesLogger.APP.recordSkippedAppActivityWithoutAllocation(
activitiesManager, node, application, schedulerKey,
ActivityDiagnosticConstant.NODE_HAS_BEEN_RESERVED, ActivityLevel.NODE);
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8 changes: 4 additions & 4 deletions ...org/apache/hadoop/yarn/server/resourcemanager/scheduler/common/fica/FiCaSchedulerApp.java
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Expand Up @@ -520,13 +520,13 @@ public boolean accept(Resource cluster,
// When reserve a resource (state == NEW is for new container,
// state == RUNNING is for increase container).
// Just check if the node is not already reserved by someone
if (schedulerContainer.getSchedulerNode().getReservedContainer()
!= null) {
RMContainer reservedContainer =
schedulerContainer.getSchedulerNode().getReservedContainer();
if (reservedContainer != null) {
if (LOG.isDebugEnabled()) {
LOG.debug("Try to reserve a container, but the node is "
+ "already reserved by another container="
+ schedulerContainer.getSchedulerNode()
.getReservedContainer().getContainerId());
+ reservedContainer.getContainerId());
}
return false;
}
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