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https://issues.apache.org/jira/browse/YARN-10642?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17287713#comment-17287713
]
zhengchenyu edited comment on YARN-10642 at 2/20/21, 3:28 PM:
--------------------------------------------------------------
YARN-10221 is the same problem, but no real reason, my issue seems more
detailed. Just use Iterator() could solve this problem. You could see nextNode
in LinkedBlockingQueue.Itr, it handle the special situation which node point
itself. So I fixed in patch YARN-10642.patch.
{code}
/**
* Returns the next live successor of p, or null if no such.
*
* Unlike other traversal methods, iterators need to handle both:
* - dequeued nodes (p.next == p)
* - (possibly multiple) interior removed nodes (p.item == null)
*/
private Node<E> nextNode(Node<E> p) {
for (;;) {
Node<E> s = p.next;
if (s == p)
return head.next;
if (s == null || s.item != null)
return s;
p = s;
}
}
{code}
was (Author: zhengchenyu):
YARN-10221 is the same problem, but no real reason, my issue seems more
detailed. Just use Iterator() could solve this problem. You could see nextNode
in LinkedBlockingQueue.Itr, it handle the special situation which node point
itself. So I fixed in patch YARN-10642.patch.
{code}
/**
* Returns the next live successor of p, or null if no such.
*
* Unlike other traversal methods, iterators need to handle both:
* - dequeued nodes (p.next == p)
* - (possibly multiple) interior removed nodes (p.item == null)
*/
private Node<E> nextNode(Node<E> p) {
for (;;) {
Node<E> s = p.next;
if (s == p)
return head.next;
if (s == null || s.item != null)
return s;
p = s;
}
}
{code}
> ResourceManager may keep stuck, because AsyncDispatcher's
> printEventQueueDetails method stuck in an endless loop
> ----------------------------------------------------------------------------------------------------------------
>
> Key: YARN-10642
> URL: https://issues.apache.org/jira/browse/YARN-10642
> Project: Hadoop YARN
> Issue Type: Bug
> Components: resourcemanager
> Affects Versions: 3.2.1
> Reporter: zhengchenyu
> Assignee: zhengchenyu
> Priority: Critical
> Attachments: MockForDeadLoop.java, YARN-10642.001.patch,
> deadloop.png, debugfornode.png, put.png, take.png
>
>
> In our cluster, ResouceManager stuck twice within twenty days. Yarn client
> can't submit application. I got jstack info at second time, then found the
> reason.
> I analyze all the jstack, I found many thread stuck because can't get
> LinkedBlockingQueue.putLock. (Note: Sorry for limited space , omit the
> analytical process)
> The reason is that one thread hold the putLock all the time,
> printEventQueueDetails will called forEachRemaining, then hold putLock and
> readLock. The AsyncDispatcher will stuck.
> {code}
> Thread 6526 (IPC Server handler 454 on default port 8030):
> State: RUNNABLE
> Blocked count: 29988
> Waited count: 2035029
> Stack:
>
> java.util.concurrent.LinkedBlockingQueue$LBQSpliterator.forEachRemaining(LinkedBlockingQueue.java:926)
> java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:482)
>
> java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:472)
> java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
> java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
> java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
>
> org.apache.hadoop.yarn.event.AsyncDispatcher$GenericEventHandler.printEventQueueDetails(AsyncDispatcher.java:270)
>
> org.apache.hadoop.yarn.event.AsyncDispatcher$GenericEventHandler.handle(AsyncDispatcher.java:295)
>
> org.apache.hadoop.yarn.server.resourcemanager.DefaultAMSProcessor.handleProgress(DefaultAMSProcessor.java:408)
>
> org.apache.hadoop.yarn.server.resourcemanager.DefaultAMSProcessor.allocate(DefaultAMSProcessor.java:215)
>
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.constraint.processor.DisabledPlacementProcessor.allocate(DisabledPlacementProcessor.java:75)
>
> org.apache.hadoop.yarn.server.resourcemanager.AMSProcessingChain.allocate(AMSProcessingChain.java:92)
>
> org.apache.hadoop.yarn.server.resourcemanager.ApplicationMasterService.allocate(ApplicationMasterService.java:432)
>
> org.apache.hadoop.yarn.api.impl.pb.service.ApplicationMasterProtocolPBServiceImpl.allocate(ApplicationMasterProtocolPBServiceImpl.java:60)
>
> org.apache.hadoop.yarn.proto.ApplicationMasterProtocol$ApplicationMasterProtocolService$2.callBlockingMethod(ApplicationMasterProtocol.java:99)
>
> org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:528)
> org.apache.hadoop.ipc.RPC$Server.call(RPC.java:1070)
> org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:1040)
> org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:958)
> java.security.AccessController.doPrivileged(Native Method)
> {code}
> I analyze LinkedBlockingQueue's source code. I found forEachRemaining in
> LinkedBlockingQueue.LBQSpliterator may stuck, when forEachRemaining and take
> are called in different thread.
> YARN-8995 introduce printEventQueueDetails method,
> "eventQueue.stream().collect" will called forEachRemaining method.
> Let's see why？ "put.png" shows that how to put("a"), "take.png" shows that
> how to take()。Specical Node: The removed Node will point itself for help gc!!!
> The key point code is in forEachRemaining, we see LBQSpliterator use
> forEachRemaining to visit all Node. But when got item value from Node, will
> release the lock. If at this time, take() will be called.
> The variable 'p' in forEachRemaining may point a Node which point itself,
> then forEachRemaining will be in dead loop. You can see it in "deadloop.png"
> Let's see a simple uni-test, Let's forEachRemaining called more slow than
> take, the problem will reproduction。uni-test is MockForDeadLoop.java.
> I debug MockForDeadLoop.java, and see a Node point itself. You can see pic
> "debugfornode.png"
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