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From Stefan Richter <s.rich...@data-artisans.com>
Subject Re: External checkpoints not getting cleaned up/discarded - potentially causing high load
Date Mon, 03 Jul 2017 10:02:04 GMT
Hi,

I have two quick questions about this problem report:

1) Which state backend are you using?
2) In case you are using RocksDB, did you also activate incremental checkpointing when moving
to Flink 1.3.

Another thing that could be really helpful, if possible, can you attach a profiler/sampling
to your job manager and figure out the hotspot methods where most time is spend? This would
be very helpful as a starting point where the problem is potentially caused.

Best,
Stefan

> Am 29.06.2017 um 18:02 schrieb Jared Stehler <jared.stehler@intellifylearning.com>:
> 
> We’re seeing our external checkpoints directory grow in an unbounded fashion… after
upgrading to Flink 1.3.  We are using Flink-Mesos.
> 
> In 1.2 (HA standalone mode), we saw (correctly) that only the latest external checkpoint
was being retained (i.e., respecting state.checkpoints.num-retained default of 1)
> 
> The Mesos-agent running the Job Manager ends up with a really high load and ends up getting
unresponsive….  Interestingly enough, there is not much CPU or Memory pressure… so it
is suggesting to us that its IO or Network bound.  But nothing jumps out at us (using iostat/netstat).
 The biggest difference seems to be external checkpoints not getting cleaned up/discarded.
 What might cause that?
> 
> ubuntu@ip-10-80-52-176:/mnt/shared/flink/ext-checkpoints$ top
> top - 13:47:41 up 16:31,  1 user,  load average: 25.85, 25.62, 25.43
> Tasks: 297 total,   1 running, 296 sleeping,   0 stopped,   0 zombie
> %Cpu(s):  0.3 us,  0.0 sy,  0.0 ni, 98.8 id,  0.7 wa,  0.0 hi,  0.0 si,  0.0 st
> KiB Mem:  32948204 total, 23974844 used,  8973360 free,   144572 buffers
> KiB Swap:        0 total,        0 used,        0 free.  7752480 cached Mem
> 
> We specify Mesos agent attributes to ensure that our Flink containers are allocated to
only a subset of the Mesos slaves…   However, we do end up with the Flink JobManager container
running on the same physical instance as multiple task manager containers. We are running
65 task managers with 2 slots each, and ~70 jobs currently on the cluster.
> 
> We use AWS EFS (https://aws.amazon.com/efs/ <https://aws.amazon.com/efs/>) mounted
on all Mesos boxes to store recovery, checkpoint, external checkpoint and save point directories.
> 
> 
>         executionEnvironment.enableCheckpointing(TimeUnit.SECONDS.toMillis(30));
> 
>         CheckpointConfig config = executionEnvironment.getCheckpointConfig();
>         config.enableExternalizedCheckpoints(ExternalizedCheckpointCleanup.RETAIN_ON_CANCELLATION);
>         config.setMinPauseBetweenCheckpoints(TimeUnit.SECONDS.toMillis(5));
> 
>         executionEnvironment.getConfig().setGlobalJobParameters(params);
>         executionEnvironment.getConfig().setAutoWatermarkInterval(watermarkInterval.getValue());
>         executionEnvironment.getConfig().setCodeAnalysisMode(CodeAnalysisMode.HINT);
> 
>         executionEnvironment.setStreamTimeCharacteristic(TimeCharacteristic.EventTime);
> 
>         // fail the job if it restarts more than 3 times in 1 minute, with 10 second
delay
>         executionEnvironment.setRestartStrategy(RestartStrategies.failureRateRestart(3,
>                 Time.minutes(2), Time.seconds(1)));
> 
>         executionEnvironment.getConfig().setLatencyTrackingInterval(30000);
> 
> 
> Would appreciate any insights you might have on this. 
> 
> Thanks
> 
> --
> Jared Stehler
> Chief Architect - Intellify Learning
> o: 617.701.6330 x703
> 
> 
> 


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