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https://issues.apache.org/jira/browse/FLINK-10672?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16887642#comment-16887642
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zhijiang commented on FLINK-10672:
----------------------------------
[~ibzib] I think it is the case of back pressure. The producer is blocked in
the process of `requestMemorySegment` because its produced partition data
could not be consumed by downstream tasks. In order to trace the root issue,
the key point is to find the proper downstream task which triggers the back
pressure.
E.G. for the topology of A-->B–>C—>D, if we found vertex A is blocked by
`requestMemorySegment` long time, we can trace the state of upstream vertex in
topology. If vertex B is also blocked, we could continue tracing the upstream
until we find the vertex which is not blocked any more, assuming vertex C in
this case. Then we further check which specific parallelism task in vertex C
causes the above serious block. Such task has a feature that its inqueue buffer
size is very high and its out queue size is low even empty, and the relevant
metrics could help. If such task is found, we could further check its stack to
confirm where it is stuck.
Maybe you could get the root cause then, or you can provide further findings
for us.
> Task stuck while writing output to flink
> ----------------------------------------
>
> Key: FLINK-10672
> URL: https://issues.apache.org/jira/browse/FLINK-10672
> Project: Flink
> Issue Type: Bug
> Components: Runtime / Coordination
> Affects Versions: 1.5.4
> Environment: OS: Debuan rodente 4.17
> Flink version: 1.5.4
> ||Key||Value||
> |jobmanager.heap.mb|1024|
> |jobmanager.rpc.address|localhost|
> |jobmanager.rpc.port|6123|
> |metrics.reporter.jmx.class|org.apache.flink.metrics.jmx.JMXReporter|
> |metrics.reporter.jmx.port|9250-9260|
> |metrics.reporters|jmx|
> |parallelism.default|1|
> |rest.port|8081|
> |taskmanager.heap.mb|1024|
> |taskmanager.numberOfTaskSlots|1|
> |web.tmpdir|/tmp/flink-web-bdb73d6c-5b9e-47b5-9ebf-eed0a7c82c26|
>
> h1. Overview
> ||Data Port||All Slots||Free Slots||CPU Cores||Physical Memory||JVM Heap
> Size||Flink Managed Memory||
> |43501|1|0|12|62.9 GB|922 MB|642 MB|
> h1. Memory
> h2. JVM (Heap/Non-Heap)
> ||Type||Committed||Used||Maximum||
> |Heap|922 MB|575 MB|922 MB|
> |Non-Heap|68.8 MB|64.3 MB|-1 B|
> |Total|991 MB|639 MB|922 MB|
> h2. Outside JVM
> ||Type||Count||Used||Capacity||
> |Direct|3,292|105 MB|105 MB|
> |Mapped|0|0 B|0 B|
> h1. Network
> h2. Memory Segments
> ||Type||Count||
> |Available|3,194|
> |Total|3,278|
> h1. Garbage Collection
> ||Collector||Count||Time||
> |G1_Young_Generation|13|336|
> |G1_Old_Generation|1|21|
> Reporter: Ankur Goenka
> Priority: Major
> Labels: beam
> Attachments: 1uruvakHxBu.png, 3aDKQ24WvKk.png, Po89UGDn58V.png,
> jmx_dump.json, jmx_dump_detailed.json, jstack_129827.log, jstack_163822.log,
> jstack_66985.log
>
>
> I am running a fairly complex pipleline with 200+ task.
> The pipeline works fine with small data (order of 10kb input) but gets stuck
> with a slightly larger data (300kb input).
>
> The task gets stuck while writing the output toFlink, more specifically it
> gets stuck while requesting memory segment in local buffer pool. The Task
> manager UI shows that it has enough memory and memory segments to work with.
> The relevant stack trace is
> {quote}"grpc-default-executor-0" #138 daemon prio=5 os_prio=0
> tid=0x00007fedb0163800 nid=0x30b7f in Object.wait() [0x00007fedb4f90000]
> java.lang.Thread.State: TIMED_WAITING (on object monitor)
> at (C/C++) 0x00007fef201c7dae (Unknown Source)
> at (C/C++) 0x00007fef1f2aea07 (Unknown Source)
> at (C/C++) 0x00007fef1f241cd3 (Unknown Source)
> at java.lang.Object.wait(Native Method)
> - waiting on <0x00000000f6d56450> (a java.util.ArrayDeque)
> at
> org.apache.flink.runtime.io.network.buffer.LocalBufferPool.requestMemorySegment(LocalBufferPool.java:247)
> - locked <0x00000000f6d56450> (a java.util.ArrayDeque)
> at
> org.apache.flink.runtime.io.network.buffer.LocalBufferPool.requestBufferBuilderBlocking(LocalBufferPool.java:204)
> at
> org.apache.flink.runtime.io.network.api.writer.RecordWriter.requestNewBufferBuilder(RecordWriter.java:213)
> at
> org.apache.flink.runtime.io.network.api.writer.RecordWriter.sendToTarget(RecordWriter.java:144)
> at
> org.apache.flink.runtime.io.network.api.writer.RecordWriter.emit(RecordWriter.java:107)
> at
> org.apache.flink.runtime.operators.shipping.OutputCollector.collect(OutputCollector.java:65)
> at
> org.apache.flink.runtime.operators.util.metrics.CountingCollector.collect(CountingCollector.java:35)
> at
> org.apache.beam.runners.flink.translation.functions.FlinkExecutableStagePruningFunction.flatMap(FlinkExecutableStagePruningFunction.java:42)
> at
> org.apache.beam.runners.flink.translation.functions.FlinkExecutableStagePruningFunction.flatMap(FlinkExecutableStagePruningFunction.java:26)
> at
> org.apache.flink.runtime.operators.chaining.ChainedFlatMapDriver.collect(ChainedFlatMapDriver.java:80)
> at
> org.apache.flink.runtime.operators.util.metrics.CountingCollector.collect(CountingCollector.java:35)
> at
> org.apache.beam.runners.flink.translation.functions.FlinkExecutableStageFunction$MyDataReceiver.accept(FlinkExecutableStageFunction.java:230)
> - locked <0x00000000f6a60bd0> (a java.lang.Object)
> at
> org.apache.beam.sdk.fn.data.BeamFnDataInboundObserver.accept(BeamFnDataInboundObserver.java:81)
> at
> org.apache.beam.sdk.fn.data.BeamFnDataInboundObserver.accept(BeamFnDataInboundObserver.java:32)
> at
> org.apache.beam.sdk.fn.data.BeamFnDataGrpcMultiplexer$InboundObserver.onNext(BeamFnDataGrpcMultiplexer.java:139)
> at
> org.apache.beam.sdk.fn.data.BeamFnDataGrpcMultiplexer$InboundObserver.onNext(BeamFnDataGrpcMultiplexer.java:125)
> at
> org.apache.beam.vendor.grpc.v1.io.grpc.stub.ServerCalls$StreamingServerCallHandler$StreamingServerCallListener.onMessage(ServerCalls.java:248)
> at
> org.apache.beam.vendor.grpc.v1.io.grpc.ForwardingServerCallListener.onMessage(ForwardingServerCallListener.java:33)
> at
> org.apache.beam.vendor.grpc.v1.io.grpc.Contexts$ContextualizedServerCallListener.onMessage(Contexts.java:76)
> at
> org.apache.beam.vendor.grpc.v1.io.grpc.internal.ServerCallImpl$ServerStreamListenerImpl.messagesAvailable(ServerCallImpl.java:263)
> at
> org.apache.beam.vendor.grpc.v1.io.grpc.internal.ServerImpl$JumpToApplicationThreadServerStreamListener$1MessagesAvailable.runInContext(ServerImpl.java:683)
> at
> org.apache.beam.vendor.grpc.v1.io.grpc.internal.ContextRunnable.run(ContextRunnable.java:37)
> at
> org.apache.beam.vendor.grpc.v1.io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:123)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
> at java.lang.Thread.run(Thread.java:748){quote}
>
> The full stack trace and logs are attached.
> Please take a look and let me know if more information is needed.
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