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From Steven Wu <stevenz...@gmail.com>
Subject Re: Checkpoint expired before completing
Date Sat, 02 Dec 2017 22:30:03 GMT
One more question. Since I have set the "Maximum Concurrent Checkpoints" to
1. Will cascading effect still be true?

Whenever my sink operator returns to normal (in terms of latency), new
checkpoint after this point should work, right? there are no other
in-flight/concurrent checkpoints still in progress.

Or is the min pause just allowing Flink to catch up in-flight msgs in
various queues/buffers? is that the cascading impact?

On Sat, Dec 2, 2017 at 2:10 PM, Steven Wu <stevenz3wu@gmail.com> wrote:

> Stephan, thanks a lot for the explanation. Now everything makes sense to
> me. Will set the min pause.
>
> On Sat, Dec 2, 2017 at 8:58 AM, Stephan Ewen <sewen@apache.org> wrote:
>
>> Hi Steven!
>>
>> You are right, there could be some cascading effect from previous
>> checkpoints.
>> I think the best way to handle that is to set the "minimum pause between
>> checkpoints". In fact, I would actually recommend this over the checkpoint
>> interval parameter.
>>
>> The pause will allow the job to handle such effects that built up during
>> an unhealthy checkpoint. You can for example set the checkpoint interval to
>> 2 mins and set the pause to 1.5 mins. That way, if a checkpoint takes
>> longer than usual, the next one will still wait for 1.5 mins after the
>> previous one completed or expired, giving the job time to catch up.
>>
>> Best,
>> Stephan
>>
>>
>> On Fri, Dec 1, 2017 at 10:10 PM, Steven Wu <stevenz3wu@gmail.com> wrote:
>>
>>> Here is the checkpoint config. no concurrent checkpoints with 2 minute
>>> checkpoint interval and timeout.
>>>
>>> Problem is gone after redeployment. I will try if I can reproduce the
>>> issue
>>>
>>> [image: Inline image 1]
>>>
>>> On Fri, Dec 1, 2017 at 6:17 AM, Nico Kruber <nico@data-artisans.com>
>>> wrote:
>>>
>>>> Hi Steven,
>>>> by default, checkpoints time out after 10 minutes if you haven't used
>>>> CheckpointConfig#setCheckpointTimeout() to change this timeout.
>>>>
>>>> Depending on your checkpoint interval, and your number of concurrent
>>>> checkpoints, there may already be some other checkpoint processes
>>>> running while you are waiting for the first to finish. In that case,
>>>> succeeding checkpoints may also fail with a timeout. However, they
>>>> should definitely get back to normal once your sink has caught up with
>>>> all buffered events.
>>>>
>>>> I included Stefan who may shed some more light onto it, but maybe you
>>>> can help us identifying the problem by providing logs at DEBUG level
>>>> (did akka report any connection loss and gated actors? or maybe some
>>>> other error in there?) or even a minimal program to reproduce.
>>>>
>>>>
>>>> Nico
>>>>
>>>> On 01/12/17 07:36, Steven Wu wrote:
>>>> >
>>>> > org.apache.flink.runtime.checkpoint.CheckpointCoordinator -
>>>> Checkpoint
>>>> > 9353 expired before completing
>>>> >
>>>> > I might know why this happened in the first place. Our sink operator
>>>> > does synchronous HTTP post, which had a 15-mint latency spike when
>>>> this
>>>> > all started. This could block flink threads and prevent checkpoint
>>>> from
>>>> > completing in time. But I don't understand why checkpoint continued
to
>>>> > fail after HTTP post latency returned to normal. there seems to be
>>>> some
>>>> > lingering/cascading effect of previous failed checkpoints on future
>>>> > checkpoints. Only after I redeploy/restart the job an hour later,
>>>> > checkpoint starts to work again.
>>>> >
>>>> > Would appreciate any suggestions/insights!
>>>> >
>>>> > Thanks,
>>>> > Steven
>>>>
>>>>
>>>
>>
>

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