[jira] [Created] (KAFKA-20829) StreamThread floods logs with "Request joining group due to: Shutdown requested" during ▎ SHUTDOWN_APPLICATION under the classic protocol

["Souquières Adam (Jira)" <ji...@apache.org>]

Souquières Adam created KAFKA-20829:
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             Summary: StreamThread floods logs with "Request joining group due to: Shutdown requested" during              ▎ SHUTDOWN_APPLICATION under the classic protocol 
                 Key: KAFKA-20829
                 URL: https://issues.apache.org/jira/browse/KAFKA-20829
             Project: Kafka
          Issue Type: Bug
          Components: streams
    Affects Versions: 4.3.1, 4.2.1
            Reporter: Souquières Adam
            Assignee: Souquières Adam


When a Streams application triggers an app-wide shutdown (e.g., a {{StreamsUncaughtExceptionHandler}} returning {{{}SHUTDOWN_APPLICATION{}}}), every {{StreamThread}} running the classic rebalance protocol spams the logs with {{Request joining group due to: Shutdown requested}} — once per run-loop iteration, at CPU speed.

*Root cause:* {{StreamThread.maybeSendShutdown()}} executes on every loop pass. KAFKA-19054 throttled the {{log.warn(...)}} call to once per 10s, but left the {{mainConsumer.enforceRebalance("Shutdown requested")}} call unthrottled. That call reaches the unguarded {{{}AbstractCoordinator.requestRejoin{}}}, which unconditionally logs at info level ({{{}Request joining group due to: {}{}}}). Since the shutdown rebalance's {{pollPhase()}} polls non-blocking ({{{}Duration.ZERO{}}}), the loop free-spins and re-triggers the log line on every pass.

*Scope:* Classic protocol only. KIP-1071, which signals shutdown via the heartbeat, is unaffected.

*Fix:* Apply the same 10s throttle guarding the warn to the {{enforceRebalance}} call as well. The first occurrence still fires immediately, so shutdown latency is unaffected, and the periodic re-assertion remains in place as a retry safety net.



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