Jan Lukavský created BEAM-7520:
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Summary: DirectRunner timers are not strictly time ordered
Key: BEAM-7520
URL: https://issues.apache.org/jira/browse/BEAM-7520
Project: Beam
Issue Type: Bug
Components: runner-direct
Affects Versions: 2.13.0
Reporter: Jan Lukavský
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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