[
https://issues.apache.org/jira/browse/BEAM-11366?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Kenneth Knowles updated BEAM-11366:
-----------------------------------
Status: Open (was: Triage Needed)
> Dataflow and KafkaIO has erratic watermark progress due to ReaderCache
> timeouts
> -------------------------------------------------------------------------------
>
> Key: BEAM-11366
> URL: https://issues.apache.org/jira/browse/BEAM-11366
> Project: Beam
> Issue Type: Bug
> Components: runner-dataflow
> Reporter: Sam Whittle
> Assignee: Sam Whittle
> Priority: P2
>
> The ReaderCache has a default timeout of 1 minute. If the source is not
> polled within that time, the UnboundedReader is destroyed and will be
> reinitilized from the checkpoint when next polled. This is too short for runs
> where the source is not polled for a while due to other keys to process. In
> particular this seems to affect Streaming engine pipelines with backlog.
> From an initial look, recovery from the Kafka UnboundedReader checkpoint does
> not seem to use the previous watermark for initializing the timestamp policy
> and perhaps the timestamp policy will return unknown watermark if it has not
> yet observed a record.
> So possible fixes would be:
> - make cache timeout configurable, or maybe dynamic, and increase it
> - ensure that KafkaIO recovery from checkpoints initializes the watermark
> properly so that cache eviction does not matter for watermark smoothness
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
