KAFKA-20404: Replace bulk TaskManager atomicity exclude with a field-level suppression#22340
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…level suppression Removes TaskManager from the bulk Or block for AT_STALE_THREAD_WRITE_OF_PRIMITIVE and adds a targeted suppression for the single field SpotBugs flags, rebalanceInProgress. rebalanceInProgress is written from the ConsumerRebalanceListener callbacks (handleRebalanceStart / handleRebalanceComplete, invoked from KafkaConsumer.poll()) and read from StreamThread.runLoop and TaskManager's commit paths. All of these run on the StreamThread, so a stale cross-thread write cannot occur and the SpotBugs warning is a false positive. Third PR in the KAFKA-20404 series after StreamThread (apache#22320) and DefaultStateUpdater (apache#22333).
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Background
KAFKA-20404 tracks replacing the bulk SpotBugs atomicity excludes (introduced when SpotBugs was upgraded from 4.8.6 to 4.9.4) with per-field investigations. This PR handles
TaskManager, the third class in the series afterStreamThread(#22320) andDefaultStateUpdater(#22333).Investigation
After removing
TaskManagerfrom the single bulkAT_STALE_THREAD_WRITE_OF_PRIMITIVEblock it appeared in (trunk line 602), SpotBugs reports exactly one field with warnings:rebalanceInProgressatTaskManager.java:102, flagged at line 191 (handleRebalanceStart) and line 208 (handleRebalanceComplete).Walking the call sites:
handleRebalanceStart/handleRebalanceComplete) are invoked fromStreamsPartitionAssignorandDefaultStreamsRebalanceListener— both areConsumerRebalanceListenercallbacks fired from insideKafkaConsumer.poll(), which is driven by theStreamThread.rebalanceInProgress()getter happen atStreamThread.runLoop(lines 938 and 962).TaskManager.java:1883(maybeCommitActiveTasksPerUserRequested) andTaskManager.java:1897(commitTasksAndMaybeUpdateCommittableOffsets) are reached only fromTaskManager.commit(...)/StreamThread.runOnce*, which also run on theStreamThread.So
rebalanceInProgressis thread-confined to theStreamThread, and the SpotBugs warning is a false positive.Changes
TaskManagerfrom the bulk<Or>block.<Match>block scoped to the class plus therebalanceInProgressfield, with a rationale comment explaining the thread-confinement.Verification
:streams:spotbugsMain --rerun-tasksclean.:streams:spotbugsTest/:streams:checkstyleMain/:streams:checkstyleTestclean.:streams:test --tests "*TaskManager*"all green.