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https://issues.apache.org/jira/browse/YARN-4752?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15885081#comment-15885081
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zhangshilong commented on YARN-4752:
------------------------------------
[~kasha] I found one problem.
In FSLeafQueue: I think resourceUsage of app should not be changed in
assignContainer because FairShareComparator uses resourceUsage to sort Apps.
{code:java}
private TreeSet<FSAppAttempt> fetchAppsWithDemand() {
TreeSet<FSAppAttempt> pendingForResourceApps =
new TreeSet<>(policy.getComparator());
readLock.lock();
try {
for (FSAppAttempt app : runnableApps) {
Resource pending = app.getAppAttemptResourceUsage().getPending();
if (!pending.equals(none())) {
pendingForResourceApps.add(app);
}
}
} finally {
readLock.unlock();
}
return pendingForResourceApps;
}
{code}
But In FSPreemptionThread
run->preemptContainers->app.trackContainerForPreemption
preemptedResources of app will be changed without FairScheduler Lock.
So getResourceUsage of App will be changed in function: assignContainer in
FSLeafQueue.
{code:java}
@Override
public Resource getResourceUsage() {
/*
* getResourcesToPreempt() returns zero, except when there are containers
* to preempt. Avoid creating an object in the common case.
*/
return getPreemptedResources().equals(Resources.none())
? getCurrentConsumption()
: Resources.subtract(getCurrentConsumption(), getPreemptedResources());
}
{code}
> FairScheduler should preempt for a ResourceRequest and all preempted
> containers should be on the same node
> ----------------------------------------------------------------------------------------------------------
>
> Key: YARN-4752
> URL: https://issues.apache.org/jira/browse/YARN-4752
> Project: Hadoop YARN
> Issue Type: Bug
> Components: fairscheduler
> Affects Versions: 2.8.0
> Reporter: Karthik Kambatla
> Assignee: Karthik Kambatla
> Fix For: 2.9.0, 3.0.0-alpha2
>
> Attachments: yarn-4752-1.patch, yarn-4752.2.patch, yarn-4752.3.patch,
> yarn-4752.4.patch, yarn-4752.4.patch,
> YARN-4752.FairSchedulerPreemptionOverhaul.pdf, yarn-6076-branch-2.1.patch
>
>
> A number of issues have been reported with respect to preemption in
> FairScheduler along the lines of:
> # FairScheduler preempts resources from nodes even if the resultant free
> resources cannot fit the incoming request.
> # Preemption doesn't preempt from sibling queues
> # Preemption doesn't preempt from sibling apps under the same queue that is
> over its fairshare
> # ...
> Filing this umbrella JIRA to group all the issues together and think of a
> comprehensive solution.
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