In practice, restriction tracker methods are called via a RestrictionTrackerObserver, which synchronizes (https://github.com/apache/beam/blob/master/sdks/java/fn-execution/src/main/java/org/apache/beam/sdk/fn/splittabledofn/RestrictionTrackers.java)
-----Original Message----- From: Jan Lukavský <je...@seznam.cz> Sent: Thursday, July 29, 2021 1:59 PM To: dev@beam.apache.org Subject: Synchronization of RestrictionTrackers Hi, I have come across something that looks like a bug to me, but I'm not sure of that. If I understand it correctly, RestrictionTracker.trySplit() and RestrictionTracker.tryClaim() methods are necessarily called from different threads. That implies, that modifying some fields inside these methods might require synchronization. Looking here [1], I didn't find anything that should ensure atomicity and consistency of these methods. If anything I'd expect the lastClaimedOffset and lastAttemptedOffset be volatile. But probably the problem is deeper. Is this a bug, or am I missing something? Jan [1] https://github.com/apache/beam/blob/939fa99ce943a30da46cb3d67c924d524fbf1be4/sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/splittabledofn/OffsetRangeTracker.java#L44
