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https://issues.apache.org/jira/browse/BEAM-8347?focusedWorklogId=337317&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-337317
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ASF GitHub Bot logged work on BEAM-8347:
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Author: ASF GitHub Bot
Created on: 01/Nov/19 14:01
Start Date: 01/Nov/19 14:01
Worklog Time Spent: 10m
Work Description: drobert commented on issue #9820: [BEAM-8347]:
Consistently advance UnboundedRabbitMqReader watermark
URL: https://github.com/apache/beam/pull/9820#issuecomment-548798382
> Instead of changing the overall watermark advance behavior, it would make
sense to provide for user to define the way to update the watermark.
I have a few concerns here, though this idea did cross my mind.
1. I'm having a hard time envisioning another reasonable watermarking
strategy. The only real context is 'delivery time', which as noted will be
FIFO, so I'm not sure what situation would cause the strategy in this PR to be
inappropriate
2. Pluggable strategies feel like they ought to be a separate PR. It's a
larger problem, and I'd set out to solve the more immediate, which is that the
current strategy fails with low message counts.
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Issue Time Tracking
-------------------
Worklog Id: (was: 337317)
Time Spent: 1h 40m (was: 1.5h)
> UnboundedRabbitMqReader can fail to advance watermark if no new data comes in
> -----------------------------------------------------------------------------
>
> Key: BEAM-8347
> URL: https://issues.apache.org/jira/browse/BEAM-8347
> Project: Beam
> Issue Type: Bug
> Components: io-java-rabbitmq
> Affects Versions: 2.15.0
> Environment: testing has been done using the DirectRunner. I also
> have DataflowRunner available
> Reporter: Daniel Robert
> Assignee: Jean-Baptiste Onofré
> Priority: Major
> Time Spent: 1h 40m
> Remaining Estimate: 0h
>
> I stumbled upon this and then saw a similar StackOverflow post:
> [https://stackoverflow.com/questions/55736593/apache-beam-rabbitmqio-watermark-doesnt-advance]
> When calling `advance()` if there are no messages, no state changes,
> including no changes to the CheckpointMark or Watermark. If there is a
> relatively constant rate of new messages coming in, this is not a problem. If
> data is bursty, and there are periods of no new messages coming in, the
> watermark will never advance.
> Contrast this with some of the logic in PubsubIO which will make provisions
> for periods of inactivity to advance the watermark (although it, too, is
> imperfect: https://issues.apache.org/jira/browse/BEAM-7322 )
> The example given in the StackOverflow post is something like this:
>
> {code:java}
> pipeline
> .apply(RabbitMqIO.read()
> .withUri("amqp://guest:guest@localhost:5672")
> .withQueue("test")
> .apply("Windowing",
> Window.<RabbitMqMessage>into(
> FixedWindows.of(Duration.standardSeconds(10)))
> .triggering(AfterWatermark.pastEndOfWindow())
> .withAllowedLateness(Duration.ZERO)
> .accumulatingFiredPanes()){code}
> If I push 2 messages into my rabbit queue, I see 2 unack'd messages and a
> window that never performs an on time trigger.
>
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