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  1. Core Server
  2. SERVER-40250

High contention for ReplicationCoordinatorImpl::_mutex in w:majority workloads

    • Type: Icon: Bug Bug
    • Resolution: Duplicate
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: None
    • Component/s: Replication
    • Labels:
    • Replication
    • ALL

      bartle reports high contention for the replication coordinator mutex in heavy insert workloads with w:majority writes, which leads to low CPU utilization and bottlenecking on a synthetic resource (the mutex). This is problematic on deployments with many cores, but can even be a problem on 16-core machines, as he mentions in a comment on another ticket.

      Shortening the critical section under the mutex in setMyLastAppliedOpTimeForward and particularly in _wakeReadyWaiters_inlock is one possible approach to mitigating the problem. Finer grained locking around waiters might be another.

            backlog-server-repl [DO NOT USE] Backlog - Replication Team
            schwerin@mongodb.com Andy Schwerin
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