GitHub user migesok added a comment to the discussion: Why AsyncWriteJournal.Resequencer is needed?
After some experiments and diving into Akka 2.6 and Pekko code, I came to this: I'm almost certain that neither for a classic persistent actor, nor for a typed, one can observe differences in behaviour between AsyncWriteJournal with and without resequencer. It is because - persistent actors inside 1 "incarnation" (between restarts) never do 2 asyncWriteMessages calls simultaneously, they are always done 1 after another - persistent actors discard and ignore asyncWriteMessages result responses from requests initiated by different "incarnations" of the same actor (courtesy of `actorInstanceId`) So the only way to observe differences in behaviour with and without resequencer is to stage an interplay between 2 persistent actors, giving them commands to persist events, and observing order in which replies come back. It should never be visible if you look at isolated actors. On one hand, resequencer can be dropped altogether, on another - could there be systems around which really depend on such intricate ordering guarantees which manifests only when several persistent actors work together? Possible but unlikely. To be on the safe side, resequencer switch could be a plugin level config option. My current plan is to roll out the change first inside our codebase. We are still running mostly on Akka 2.6 with Pekko migration in progress, using in-house journal and snapshot plugins. Then we will try to backport it to Pekko, if maintainers agree to take it. GitHub link: https://github.com/apache/pekko/discussions/1881#discussioncomment-13367927 ---- This is an automatically sent email for notifications@pekko.apache.org. To unsubscribe, please send an email to: notifications-unsubscr...@pekko.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: notifications-unsubscr...@pekko.apache.org For additional commands, e-mail: notifications-h...@pekko.apache.org
