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From Seth Wiesman <swies...@mediamath.com>
Subject Re: state size in relation to cluster size and processing speed
Date Fri, 23 Dec 2016 19:28:06 GMT
Watermarks are generated using the PeriodicWatermarkAssigner using a timestamp field from within
the records. We are processing log data from an S3 bucket and logs are always processed in
chronological order using a custom ContinuousFileMonitoringFunction but the standard ContinousFileReaderOperator.
Certainly with a larger cluster splits would be processed more quickly and as such the watermark
would advance at a quicker pace. Why do you think a more quickly advancing watermark would
affect state size in this case?

Seth Wiesman

From: Aljoscha Krettek <aljoscha@apache.org>
Reply-To: "user@flink.apache.org" <user@flink.apache.org>
Date: Friday, December 23, 2016 at 1:43 PM
To: "user@flink.apache.org" <user@flink.apache.org>
Subject: Re: state size in relation to cluster size and processing speed

how are you generating your watermarks? Could it be that they advance faster when the job
is processing more data?


On Fri, 16 Dec 2016 at 21:01 Seth Wiesman <swiesman@mediamath.com<mailto:swiesman@mediamath.com>>

I’ve noticed something peculiar about the relationship between state size and cluster size
and was wondering if anyone here knows of the reason. I am running a job with 1 hour tumbling
event time windows which have an allowed lateness of 7 days. When I run on a 20-node cluster
with FsState I can process approximately 1.5 days’ worth of data in an hour with the most
recent checkpoint being ~20gb.  Now if I run the same job with the same configurations on
a 40-node cluster I can process 2 days’ worth of data in 20 min (expected) but the state
size is only ~8gb. Because allowed lateness is 7 days no windows should be purged yet and
I would expect the larger cluster which has processed more data to have a larger state. Is
there some why a slower running job or a smaller cluster would require more state?

This is more of a curiosity than an issue. Thanks’ in advance for any insights you may have.

Seth Wiesman
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