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https://issues.apache.org/jira/browse/YARN-10848?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17390099#comment-17390099
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Prabhu Joseph commented on YARN-10848:
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Hi [~pbacsko], IMO this is breaking the existing behavior of
DefaultResourceCalculator. DefaultResourceCalculator is useful when the
workloads are not CPU intensive like MapReduce, Tez and user need not worry on
CPU configurations here.
>> IMO whether a container "fits in" or not should depend on both values
DominantResourceCalaculator provides this support which users configures if
they want to consider both memory and cpu resources in scheduling.
> Vcore allocation problem with DefaultResourceCalculator
> -------------------------------------------------------
>
> Key: YARN-10848
> URL: https://issues.apache.org/jira/browse/YARN-10848
> Project: Hadoop YARN
> Issue Type: Bug
> Components: capacity scheduler, capacityscheduler
> Reporter: Peter Bacsko
> Assignee: Minni Mittal
> Priority: Major
> Labels: pull-request-available
> Attachments: TestTooManyContainers.java
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> If we use DefaultResourceCalculator, then Capacity Scheduler keeps allocating
> containers even if we run out of vcores.
> CS checks the the available resources at two places. The first check is
> {{CapacityScheduler.allocateContainerOnSingleNode()}}:
> {noformat}
> if (calculator.computeAvailableContainers(Resources
> .add(node.getUnallocatedResource(),
> node.getTotalKillableResources()),
> minimumAllocation) <= 0) {
> LOG.debug("This node " + node.getNodeID() + " doesn't have sufficient "
> + "available or preemptible resource for minimum allocation");
> {noformat}
> The second, which is more important, is located in
> {{RegularContainerAllocator.assignContainer()}}:
> {noformat}
> if (!Resources.fitsIn(rc, capability, totalResource)) {
> LOG.warn("Node : " + node.getNodeID()
> + " does not have sufficient resource for ask : " + pendingAsk
> + " node total capability : " + node.getTotalResource());
> // Skip this locality request
> ActivitiesLogger.APP.recordSkippedAppActivityWithoutAllocation(
> activitiesManager, node, application, schedulerKey,
> ActivityDiagnosticConstant.
> NODE_TOTAL_RESOURCE_INSUFFICIENT_FOR_REQUEST
> + getResourceDiagnostics(capability, totalResource),
> ActivityLevel.NODE);
> return ContainerAllocation.LOCALITY_SKIPPED;
> }
> {noformat}
> Here, {{rc}} is the resource calculator instance, the other two values are:
> {noformat}
> Resource capability = pendingAsk.getPerAllocationResource();
> Resource available = node.getUnallocatedResource();
> {noformat}
> There is a repro unit test attatched to this case, which can demonstrate the
> problem. The root cause is that we pass the resource calculator to
> {{Resource.fitsIn()}}. Instead, we should use an overridden version, just
> like in {{FSAppAttempt.assignContainer()}}:
> {noformat}
> // Can we allocate a container on this node?
> if (Resources.fitsIn(capability, available)) {
> // Inform the application of the new container for this request
> RMContainer allocatedContainer =
> allocate(type, node, schedulerKey, pendingAsk,
> reservedContainer);
> {noformat}
> In CS, if we switch to DominantResourceCalculator OR use
> {{Resources.fitsIn()}} without the calculator in
> {{RegularContainerAllocator.assignContainer()}}, that fixes the failing unit
> test (see {{testTooManyContainers()}} in {{TestTooManyContainers.java}}).
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