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Posted to issues@beam.apache.org by "Kenneth Knowles (Jira)" <ji...@apache.org> on 2019/11/01 17:12:00 UTC
[jira] [Created] (BEAM-8543) Dataflow streaming timers are not
strictly time ordered when set earlier mid-bundle
Kenneth Knowles created BEAM-8543:
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Summary: Dataflow streaming timers are not strictly time ordered when set earlier mid-bundle
Key: BEAM-8543
URL: https://issues.apache.org/jira/browse/BEAM-8543
Project: Beam
Issue Type: Bug
Components: runner-direct
Affects Versions: 2.13.0
Reporter: Jan Lukavský
Assignee: Jan Lukavský
Fix For: 2.17.0
Let's suppose we have the following situation:
- statful ParDo with two timers - timerA and timerB
- timerA is set for window.maxTimestamp() + 1
- timerB is set anywhere between <windowStart, windowEnd), let's denote that timerB.timestamp
- input watermark moves to BoundedWindow.TIMESTAMP_MAX_VALUE
Then the order of timers is as follows (correct):
- timerB
- timerA
But, if timerB sets another timer (say for timerB.timestamp + 1), then the order of timers will be:
- timerB (timerB.timestamp)
- timerA (BoundedWindow.TIMESTAMP_MAX_VALUE)
- timerB (timerB.timestamp + 1)
Which is not ordered by timestamp. The reason for this is that when the input watermark update is evaluated, the WatermarkManager,extractFiredTimers() will produce both timerA and timerB. That would be correct, but when timerB sets another timer, that breaks this.
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