KAFKA-20404: Replace bulk DefaultStateUpdater atomicity excludes with field-level suppressions#22333
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… field-level suppressions Removes DefaultStateUpdater$StateUpdaterThread from the bulk Or blocks for AT_NONATOMIC_OPERATIONS_ON_SHARED_VARIABLE and AT_NONATOMIC_64BIT_PRIMITIVE, and adds two targeted suppressions for the single field SpotBugs actually flags, totalCheckpointLatency. totalCheckpointLatency is accumulated in measureCheckpointLatency and reset in recordMetrics. Both methods are private and only invoked from within StateUpdaterThread.runOnce, so the read-modify-write is thread-confined and the SpotBugs warnings are false positives. Second PR in the KAFKA-20404 series after StreamThread (1/N, apache#22320).
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Background
KAFKA-20404 tracks replacing the bulk SpotBugs atomicity excludes (introduced when SpotBugs was upgraded from 4.8.6 to 4.9.4) with per-field investigations. This PR handles
DefaultStateUpdater$StateUpdaterThread, the second class in the series afterStreamThread(#22320).Investigation
After removing
DefaultStateUpdater$StateUpdaterThreadfrom the two bulk excludes it appeared in (AT_NONATOMIC_OPERATIONS_ON_SHARED_VARIABLEat line 505 andAT_NONATOMIC_64BIT_PRIMITIVEat line 544 on trunk), SpotBugs reports exactly one field with warnings:totalCheckpointLatencyatDefaultStateUpdater.java:100, flagged at line 732 (measureCheckpointLatency) and line 750 (recordMetrics).Walking the call sites:
measureCheckpointLatencyisprivateand only called from withinStateUpdaterThread:restoreTasks,pauseTasks,resumeTasks,removeUpdatingTask,maybeCheckpointTasks.recordMetricsisprivateand only called fromStateUpdaterThread.runOnce(line 213).StateUpdaterThreaditself (the inner class extendsThread).So
totalCheckpointLatencyis thread-confined and the SpotBugs warnings are false positives.Changes
DefaultStateUpdater$StateUpdaterThreadfrom the two bulk<Or>blocks.<Match>blocks scoped to the class plus thetotalCheckpointLatencyfield, each with a rationale comment explaining the thread-confinement, one per bug pattern.Verification
:streams:spotbugsMain --rerun-tasksclean.:streams:checkstyleMain/:streams:checkstyleTest/:streams:spotbugsTestclean.:streams:test --tests "*DefaultStateUpdater*"all green.