[Claude] [AUTOTEST-466] Log benign setMaxInFlight teardown race at DEBUG

[sprout-autoagent]

Sentry issue EVERYDAY-POLLER-75Z files a Jira ticket whenever SubConnection.setMaxInFlight logs a SocketException: Socket closed at ERROR. The exception is a benign teardown race: during normal connection churn (nsqd rollout, k8s pod cycling, peer EOF) the dedicated read thread calls Connection.close() — setting isReading = false and closing the socket — while Subscription.distributeMaxInFlight is concurrently calling setMaxInFlight → flush() on that same connection. The IOException is already caught, the connection is closed and rebuilt by checkConnections, and no messages are lost (inFlight:0). Only the log level is wrong. This change branches the existing catch block on the isReading liveness flag — the same discriminator the sibling PubConnection.checkConnectionLiveness() already uses — so genuine failures stay at ERROR while the benign race logs at DEBUG and no longer surfaces in Sentry.

Change Summary

• src/main/java/com/sproutsocial/nsq/SubConnection.java — In the catch (IOException e) block of setMaxInFlight(int, boolean), replaced the unconditional logger.error("setMaxInFlight failed. con:{}", ...) with a branch on isReading: log at ERROR when the connection still believes it is reading (a genuine, actionable failure), and at DEBUG when isReading == false (the read thread already tore the socket down — a benign race). close() is still called unconditionally in both branches, so behaviour is unchanged. No method signatures, control flow, or callers were touched.
• src/test/java/com/sproutsocial/nsq/SubConnectionTest.java (new) — First unit test in the repo; runs under surefire with no Docker. Builds a SubConnection with mocked Client/Subscription/Subscriber, swaps in an OutputStream whose flush() throws IOException("Socket closed") (reproducing the race), and attaches a Logback ListAppender to the com.sproutsocial.nsq.SubConnection logger. logsErrorWhenFlushFailsWhileStillReading asserts the failure is logged at ERROR when isReading == true and that close() ran; logsDebugWhenFlushFailsAfterConnectionTornDown sets isReading = false and asserts the failure is logged at DEBUG with no ERROR event.

Suggested Assignee

@alex-dyla — alex.dyla@sproutsocial.com (Alex Dyla)

Related Links

• AUTOTEST-466
• worker run #26639122007
• Sentry: SocketException: Socket closed (EVERYDAY-POLLER-75Z) — Connection.flush / setMaxInFlight