Thanks, Ori

>From the log, it looks like there IS a memory leak.

At 10:12:53 there was the last "successfull" gc when 13Gb freed in
0.4653809 secs:
[Eden: 17336.0M(17336.0M)->0.0B(2544.0M) Survivors: 40960.0K->2176.0M Heap:
23280.3M(28960.0M)->10047.0M(28960.0M)]

Then the heap grew from 10G to 28G with GC not being able to free up enough
space:
[Eden: 2544.0M(2544.0M)->0.0B(856.0M) Survivors: 2176.0M->592.0M Heap:
12591.0M(28960.0M)->11247.0M(28960.0M)]
[Eden: 856.0M(856.0M)->0.0B(1264.0M) Survivors: 592.0M->184.0M Heap:
12103.0M(28960.0M)->11655.0M(28960.0M)]
[Eden: 1264.0M(1264.0M)->0.0B(1264.0M) Survivors: 184.0M->184.0M Heap:
12929.0M(28960.0M)->12467.0M(28960.0M)]
... ...
[Eden: 1264.0M(1264.0M)->0.0B(1264.0M) Survivors: 184.0M->184.0M Heap:
28042.6M(28960.0M)->27220.6M(28960.0M)]
[Eden: 1264.0M(1264.0M)->0.0B(1264.0M) Survivors: 184.0M->184.0M Heap:
28494.5M(28960.0M)->28720.6M(28960.0M)]
[Eden: 224.0M(1264.0M)->0.0B(1448.0M) Survivors: 184.0M->0.0B Heap:
28944.6M(28960.0M)->28944.6M(28960.0M)]

Until 10:15:12 when GC freed almost 4G - but it took 51 seconds and
heartbeat timed out:
2020-07-01T10:15:12.869+0000: [Full GC (Allocation Failure)
 28944M->26018M(28960M), 51.5256128 secs]
  [Eden: 0.0B(1448.0M)->0.0B(1448.0M) Survivors: 0.0B->0.0B Heap:
28944.6M(28960.0M)->26018.9M(28960.0M)], [Metaspace:
113556K->112729K(1150976K)]
  [Times: user=91.08 sys=0.06, real=51.53 secs]
2020-07-01T10:16:04.395+0000: [GC concurrent-mark-abort]
10:16:04.398 [flink-akka.actor.default-dispatcher-21] INFO
 org.apache.flink.runtime.taskexecutor.TaskExecutor  - The heartbeat of
JobManager with id bc59ba6a

No substantial amount memory was freed after that.

If this memory usage pattern is expected, I'd suggest to:
1. increase heap size
2. play with PrintStringDeduplicationStatistics and UseStringDeduplication
flags - probably string deduplication is making G1 slower then CMS

Regards,
Roman


On Thu, Jul 2, 2020 at 10:11 AM Ori Popowski <ori....@gmail.com> wrote:

> Hi,
>
> I'd be happy to :) Attached is a TaskManager log which timed out.
>
>
> Thanks!
>
> On Thu, Jul 2, 2020 at 4:21 AM Xintong Song <tonysong...@gmail.com> wrote:
>
>> Maybe you can share the log and gc-log of the problematic TaskManager?
>> See if we can find any clue.
>>
>> Thank you~
>>
>> Xintong Song
>>
>>
>>
>> On Wed, Jul 1, 2020 at 8:11 PM Ori Popowski <ori....@gmail.com> wrote:
>>
>>> I've found out that sometimes one of my TaskManagers experiences a GC
>>> pause of 40-50 seconds and I have no idea why.
>>> I profiled one of the machines using JProfiler and everything looks
>>> fine. No memory leaks, memory is low.
>>> However, I cannot anticipate which of the machines will get the 40-50
>>> seconds pause and I also cannot profile all of them all the time.
>>>
>>> Any suggestions?
>>>
>>> On Mon, Jun 29, 2020 at 4:44 AM Xintong Song <tonysong...@gmail.com>
>>> wrote:
>>>
>>>> In Flink 1.10, there's a huge change in the memory management compared
>>>> to previous versions. This could be related to your observations, because
>>>> with the same configurations, it is possible that there's less JVM heap
>>>> space (with more off-heap memory). Please take a look at this migration
>>>> guide [1].
>>>>
>>>> Thank you~
>>>>
>>>> Xintong Song
>>>>
>>>>
>>>> [1]
>>>> https://ci.apache.org/projects/flink/flink-docs-release-1.10/ops/memory/mem_migration.html
>>>>
>>>> On Sun, Jun 28, 2020 at 10:12 PM Ori Popowski <ori....@gmail.com>
>>>> wrote:
>>>>
>>>>> Thanks for the suggestions!
>>>>>
>>>>> > i recently tried 1.10 and see this error frequently. and i dont have
>>>>> the same issue when running with 1.9.1
>>>>> I did downgrade to Flink 1.9 and there's certainly no change in the
>>>>> occurrences in the heartbeat timeout
>>>>>
>>>>>
>>>>> >
>>>>>
>>>>>    - Probably the most straightforward way is to try increasing the
>>>>>    timeout to see if that helps. You can leverage the configuration option
>>>>>    `heartbeat.timeout`[1]. The default is 50s.
>>>>>    - It might be helpful to share your configuration setups (e.g.,
>>>>>    the TM resources, JVM parameters, timeout, etc.). Maybe the easiest 
>>>>> way is
>>>>>    to share the beginning part of your JM/TM logs, including the JVM
>>>>>    parameters and all the loaded configurations.
>>>>>    - You may want to look into the GC logs in addition to the
>>>>>    metrics. In case of a CMS GC stop-the-world, you may not be able to 
>>>>> see the
>>>>>    most recent metrics due to the process not responding to the metric
>>>>>    querying services.
>>>>>    - You may also look into the status of the JM process. If JM is
>>>>>    under significant GC pressure, it could also happen that the heartbeat
>>>>>    message from TM is not timely handled before the timeout check.
>>>>>    - Is there any metrics monitoring the network condition between
>>>>>    the JM and timeouted TM? Possibly any jitters?
>>>>>
>>>>>
>>>>> Weirdly enough, I did manage to find a problem with the timed out
>>>>> TaskManagers, which slipped away the last time I checked: The timed out
>>>>> TaskManager is always the one with the max. GC time (young generation). I
>>>>> see it only now that I run with G1GC, but with the previous GC it wasn't
>>>>> the case.
>>>>>
>>>>> Does anyone know what can cause high GC time and how to mitigate this?
>>>>>
>>>>> On Sun, Jun 28, 2020 at 5:04 AM Xintong Song <tonysong...@gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Hi Ori,
>>>>>>
>>>>>> Here are some suggestions from my side.
>>>>>>
>>>>>>    - Probably the most straightforward way is to try increasing the
>>>>>>    timeout to see if that helps. You can leverage the configuration 
>>>>>> option
>>>>>>    `heartbeat.timeout`[1]. The default is 50s.
>>>>>>    - It might be helpful to share your configuration setups (e.g.,
>>>>>>    the TM resources, JVM parameters, timeout, etc.). Maybe the easiest 
>>>>>> way is
>>>>>>    to share the beginning part of your JM/TM logs, including the JVM
>>>>>>    parameters and all the loaded configurations.
>>>>>>    - You may want to look into the GC logs in addition to the
>>>>>>    metrics. In case of a CMS GC stop-the-world, you may not be able to 
>>>>>> see the
>>>>>>    most recent metrics due to the process not responding to the metric
>>>>>>    querying services.
>>>>>>    - You may also look into the status of the JM process. If JM is
>>>>>>    under significant GC pressure, it could also happen that the heartbeat
>>>>>>    message from TM is not timely handled before the timeout check.
>>>>>>    - Is there any metrics monitoring the network condition between
>>>>>>    the JM and timeouted TM? Possibly any jitters?
>>>>>>
>>>>>>
>>>>>> Thank you~
>>>>>>
>>>>>> Xintong Song
>>>>>>
>>>>>>
>>>>>> [1]
>>>>>> https://ci.apache.org/projects/flink/flink-docs-release-1.10/ops/config.html#heartbeat-timeout
>>>>>>
>>>>>> On Thu, Jun 25, 2020 at 11:15 PM Ori Popowski <ori....@gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> Hello,
>>>>>>>
>>>>>>> I'm running Flink 1.10 on EMR and reading from Kafka with 189
>>>>>>> partitions and I have parallelism of 189.
>>>>>>>
>>>>>>> Currently running with RocksDB, with checkpointing disabled. My
>>>>>>> state size is appx. 500gb.
>>>>>>>
>>>>>>> I'm getting sporadic "Heartbeat of TaskManager timed out" errors
>>>>>>> with no apparent reason.
>>>>>>>
>>>>>>> I check the container that gets the timeout for GC pauses, heap
>>>>>>> memory, direct memory, mapped memory, offheap memory, CPU load, network
>>>>>>> load, total out-records, total in-records, backpressure, and everything 
>>>>>>> I
>>>>>>> can think of. But all those metrics show that there's nothing unusual, 
>>>>>>> and
>>>>>>> it has around average values for all those metrics. There are a lot of
>>>>>>> other containers which score higher.
>>>>>>>
>>>>>>> All the metrics are very low because every TaskManager runs on a
>>>>>>> r5.2xlarge machine alone.
>>>>>>>
>>>>>>> I'm trying to debug this for days and I cannot find any explanation
>>>>>>> for it.
>>>>>>>
>>>>>>> Can someone explain why it's happening?
>>>>>>>
>>>>>>> java.util.concurrent.TimeoutException: Heartbeat of TaskManager
>>>>>>> with id container_1593074931633_0011_01_000127 timed out.
>>>>>>>     at org.apache.flink.runtime.jobmaster.
>>>>>>> JobMaster$TaskManagerHeartbeatListener.notifyHeartbeatTimeout(
>>>>>>> JobMaster.java:1147)
>>>>>>>     at org.apache.flink.runtime.heartbeat.HeartbeatMonitorImpl.run(
>>>>>>> HeartbeatMonitorImpl.java:109)
>>>>>>>     at java.util.concurrent.Executors$RunnableAdapter.call(Executors
>>>>>>> .java:511)
>>>>>>>     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
>>>>>>>     at org.apache.flink.runtime.rpc.akka.AkkaRpcActor
>>>>>>> .handleRunAsync(AkkaRpcActor.java:397)
>>>>>>>     at org.apache.flink.runtime.rpc.akka.AkkaRpcActor
>>>>>>> .handleRpcMessage(AkkaRpcActor.java:190)
>>>>>>>     at org.apache.flink.runtime.rpc.akka.FencedAkkaRpcActor
>>>>>>> .handleRpcMessage(FencedAkkaRpcActor.java:74)
>>>>>>>     at org.apache.flink.runtime.rpc.akka.AkkaRpcActor.handleMessage(
>>>>>>> AkkaRpcActor.java:152)
>>>>>>>     at akka.japi.pf.UnitCaseStatement.apply(CaseStatements.scala:26)
>>>>>>>     at akka.japi.pf.UnitCaseStatement.apply(CaseStatements.scala:21)
>>>>>>>     at scala.PartialFunction$class.applyOrElse(PartialFunction
>>>>>>> .scala:123)
>>>>>>>     at akka.japi.pf.UnitCaseStatement.applyOrElse(CaseStatements
>>>>>>> .scala:21)
>>>>>>>     at scala.PartialFunction$OrElse.applyOrElse(PartialFunction
>>>>>>> .scala:170)
>>>>>>>     at scala.PartialFunction$OrElse.applyOrElse(PartialFunction
>>>>>>> .scala:171)
>>>>>>>     at scala.PartialFunction$OrElse.applyOrElse(PartialFunction
>>>>>>> .scala:171)
>>>>>>>     at akka.actor.Actor$class.aroundReceive(Actor.scala:517)
>>>>>>>     at akka.actor.AbstractActor.aroundReceive(AbstractActor.scala:
>>>>>>> 225)
>>>>>>>     at akka.actor.ActorCell.receiveMessage(ActorCell.scala:592)
>>>>>>>     at akka.actor.ActorCell.invoke(ActorCell.scala:561)
>>>>>>>     at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:258)
>>>>>>>     at akka.dispatch.Mailbox.run(Mailbox.scala:225)
>>>>>>>     at akka.dispatch.Mailbox.exec(Mailbox.scala:235)
>>>>>>>     at akka.dispatch.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:
>>>>>>> 260)
>>>>>>>     at akka.dispatch.forkjoin.ForkJoinPool$WorkQueue.runTask(
>>>>>>> ForkJoinPool.java:1339)
>>>>>>>     at akka.dispatch.forkjoin.ForkJoinPool.runWorker(ForkJoinPool
>>>>>>> .java:1979)
>>>>>>>     at akka.dispatch.forkjoin.ForkJoinWorkerThread.run(
>>>>>>> ForkJoinWorkerThread.java:107)
>>>>>>>
>>>>>>> Thanks
>>>>>>>
>>>>>>

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