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https://issues.apache.org/jira/browse/YARN-6901?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16108126#comment-16108126
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Jason Lowe commented on YARN-6901:
----------------------------------
As I understand the stacktraces, we have the preemption monitor thread who has
locked a leaf queue and is in the process of trying to lock the application
within the queue. Then we have the scheduling thread which is calling
LeafQueue's assignContainers and ultimately locks an application then tries to
lock the leaf queue for that application. Is that correct? If so I'm
wondering how we're deadlocking since the thread calling
LeafQueue#assignContainers should already have the lock on the leaf queue.
Maybe I missed a spot since I couldn't line up the line numbers in the stack
trace with branch-2.8 source, but everywhere I saw LeafQueue's assignContainers
calling the application's assignContainers method it was within the context of
a {{synchronized(this)}} block.
Now I'm wondering how we did _not_ have the lock when trying to get the leaf
queue path. Are we somehow trying to examine an allocation for some other
queue, or does the queue think this application is part of this queue but the
app thinks it is part of some other queue? I'm probably missing something
basic, but I'm not sure why we don't already have the leaf queue locked when
FiCaSchedulerApp#assignContainers is called.
On a related note, I found it odd that LeafQueue#assignContainers explicitly
locks the app before callling assignContainers on it when it is trying to
assign a reserved container but I didn't see a similar lock on the application
before calling assignContainers for the non-reserved case. Seems like we're
either missing a lock we need or grabbing a lock unnecessarily.
> A CapacityScheduler app->LeafQueue deadlock found in branch-2.8
> ----------------------------------------------------------------
>
> Key: YARN-6901
> URL: https://issues.apache.org/jira/browse/YARN-6901
> Project: Hadoop YARN
> Issue Type: Bug
> Affects Versions: 2.8.0
> Reporter: Wangda Tan
> Assignee: Wangda Tan
> Priority: Blocker
> Attachments: YARN-6901.branch-2.8.001.patch
>
>
> Stacktrace:
> {code}
> Thread 22068: (state = BLOCKED)
> -
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.AbstractCSQueue.getParent()
> @bci=0, line=185 (Compiled frame)
> -
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.LeafQueue.getQueuePath()
> @bci=8, line=262 (Compiled frame)
> -
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.allocator.AbstractContainerAllocator.getCSAssignmentFromAllocateResult(org.apache.hadoop.yarn.api.records.Resource,
>
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.allocator.ContainerAllocation,
> org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainer)
> @bci=183, line=80 (Compiled frame)
> -
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.allocator.RegularContainerAllocator.assignContainers(org.apache.hadoop.yarn.api.records.Resource,
>
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.common.fica.FiCaSchedulerNode,
>
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.SchedulingMode,
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.ResourceLimits,
> org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainer)
> @bci=204, line=747 (Compiled frame)
> -
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.allocator.ContainerAllocator.assignContainers(org.apache.hadoop.yarn.api.records.Resource,
>
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.common.fica.FiCaSchedulerNode,
>
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.SchedulingMode,
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.ResourceLimits,
> org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainer)
> @bci=16, line=49 (Compiled frame)
> -
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.common.fica.FiCaSchedulerApp.assignContainers(org.apache.hadoop.yarn.api.records.Resource,
>
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.common.fica.FiCaSchedulerNode,
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.ResourceLimits,
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.SchedulingMode,
> org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainer)
> @bci=61, line=468 (Compiled frame)
> -
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.LeafQueue.assignContainers(org.apache.hadoop.yarn.api.records.Resource,
>
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.common.fica.FiCaSchedulerNode,
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.ResourceLimits,
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.SchedulingMode)
> @bci=148, line=876 (Compiled frame)
> -
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.allocateContainersToNode(org.apache.hadoop.yarn.server.resourcemanager.scheduler.common.fica.FiCaSchedulerNode)
> @bci=157, line=1149 (Compiled frame)
> -
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.handle(org.apache.hadoop.yarn.server.resourcemanager.scheduler.event.SchedulerEvent)
> @bci=266, line=1277 (Compiled frame)
> ================
> Thread 22124: (state = BLOCKED)
> -
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.SchedulerApplicationAttempt.getReservedContainers()
> @bci=0, line=336 (Compiled frame)
> -
> org.apache.hadoop.yarn.server.resourcemanager.monitor.capacity.FifoCandidatesSelector.preemptFrom(org.apache.hadoop.yarn.server.resourcemanager.scheduler.common.fica.FiCaSchedulerApp,
> org.apache.hadoop.yarn.api.records.Resource, java.util.Map, java.util.List,
> org.apache.hadoop.yarn.api.records.Resource, java.util.Map,
> org.apache.hadoop.yarn.api.records.Resource) @bci=61, line=277 (Compiled
> frame)
> -
> org.apache.hadoop.yarn.server.resourcemanager.monitor.capacity.FifoCandidatesSelector.selectCandidates(java.util.Map,
> org.apache.hadoop.yarn.api.records.Resource,
> org.apache.hadoop.yarn.api.records.Resource) @bci=374, line=138 (Compiled
> frame)
> -
> org.apache.hadoop.yarn.server.resourcemanager.monitor.capacity.ProportionalCapacityPreemptionPolicy.containerBasedPreemptOrKill(org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CSQueue,
> org.apache.hadoop.yarn.api.records.Resource) @bci=264, line=342 (Compiled
> frame)
> -
> org.apache.hadoop.yarn.server.resourcemanager.monitor.capacity.ProportionalCapacityPreemptionPolicy.editSchedule()
> @bci=34, line=202 (Compiled frame)
> -
> org.apache.hadoop.yarn.server.resourcemanager.monitor.SchedulingMonitor.invokePolicy()
> @bci=4, line=81 (Compiled frame)
> -
> org.apache.hadoop.yarn.server.resourcemanager.monitor.SchedulingMonitor$PreemptionChecker.run()
> @bci=23, line=92 (Interpreted frame)
> - java.lang.Thread.run() @bci=11, line=745 (Interpreted frame)
> {code}
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