[fix][broker] Fix race in pending acks removal in redeliverUnacknowledgedMessages#25589
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lhotari
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LGTM. Good catch! Just thinking that the usage of "expire" is slightly misleading in the title since it could be confused with "message expiration". An alternative title could be "Fix race in pending acks removal in redeliverUnacknowledgedMessages"
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Motivation
Consumer.redeliverUnacknowledgedMessageshas race conditions with the expire path (readMoreEntries → removeAllUpTo), which can corrupt theunackedMessagescounter:getandremoveseparately, allowing expire to remove entries in between and causing incorrect redelivery counting.Modifications
Make redelivery operations atomic with respect to expire:
PendingAcksMap.forEachAndClear()to atomically iterate and clear all entries under a single lock.PendingAcksMap.removeAndGet()to atomically get and remove entries.