Introduce CMS_COMMIT stage for serialized commit handling#4891
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Add a dedicated single-threaded CMS_COMMIT stage to prevent INTERNAL_METADATA pool exhaustion under concurrent TCM_COMMIT_REQ load. Multiple threads entering AbstractLocalProcessor.commit() simultaneously amplify LWT retry pressure. Switching to a single commit thread eliminates that without reducing useful throughput since Paxos serializes the actual log write anyway. Patch by Jon Meredith; reviewed by Sam Tunnicliffe for CASSANDRA-21454
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Add a dedicated single-threaded CMS_COMMIT stage to prevent INTERNAL_METADATA pool exhaustion under concurrent TCM_COMMIT_REQ load. Multiple threads entering AbstractLocalProcessor.commit() simultaneously amplify LWT retry pressure. Switching to a single commit thread eliminates that without reducing useful throughput since Paxos serializes the actual log write anyway.
Patch by Jon Meredith; reviewed by Sam Tunnicliffe for CASSANDRA-21454