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https://issues.apache.org/jira/browse/BEAM-9308?focusedWorklogId=391041&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-391041
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ASF GitHub Bot logged work on BEAM-9308:
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Author: ASF GitHub Bot
Created on: 22/Feb/20 03:36
Start Date: 22/Feb/20 03:36
Worklog Time Spent: 10m
Work Description: steveniemitz commented on issue #10852: [BEAM-9308]
Decorrelate state cleanup timers
URL: https://github.com/apache/beam/pull/10852#issuecomment-589913494
> Why is this problem specific to the GC timer? How about the normal
end-of-window timer that is used to fire windowed aggregations. For fixed
windows there is one per key and those also fire all at the same time.
heh, we already work around that on our own by using state + timers instead
of the built-in combine transform. We already decorrelate our end-of-window
triggering (and we're now using the watermark hold feature for timers which
simplified things a lot), but can't work around the state GC w/o changing the
worker itself.
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Issue Time Tracking
-------------------
Worklog Id: (was: 391041)
Time Spent: 1h 20m (was: 1h 10m)
> Optimize state cleanup at end-of-window
> ---------------------------------------
>
> Key: BEAM-9308
> URL: https://issues.apache.org/jira/browse/BEAM-9308
> Project: Beam
> Issue Type: Improvement
> Components: runner-dataflow
> Reporter: Steve Niemitz
> Assignee: Steve Niemitz
> Priority: Major
> Time Spent: 1h 20m
> Remaining Estimate: 0h
>
> When using state with a large keyspace, you can end up with a large amount of
> state cleanup timers set to fire all 1ms after the end of a window. This can
> cause a momentary (I've observed 1-3 minute) lag in processing while windmill
> and the java harness fire and process these cleanup timers.
> By spreading the firing over a short period after the end of the window, we
> can decorrelate the firing of the timers and smooth the load out, resulting
> in much less impact from state cleanup.
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