xzhang2sc commented on issue #31510: URL: https://github.com/apache/beam/issues/31510#issuecomment-2354113404
I think the issue is how watermark is estimated in [PubsubUnboundedSource](https://github.com/apache/beam/blob/master/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/pubsub/PubsubUnboundedSource.java#L95C10-L100C7). The assumption of Pubsub delivering the oldest message at least once a minute is quite fragile, the improperly progressed watermark will result in old messages delivered repeatedly. The Dataflow watermark estimation is more sophisticated, and it utilizes the "oldest unacked publish timestamp" metric: https://stackoverflow.com/questions/42169004/what-is-the-watermark-heuristic-for-pubsubio-running-on-gcd -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
