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  1. Core Server
  2. SERVER-40723

Deadlock between S lock acquisition on secondary and prepare conflict

    • Type: Icon: Bug Bug
    • Resolution: Duplicate
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: None
    • Component/s: Replication
    • Labels:
    • ALL
    • Repl 2019-05-06

      The following deadlock can occur:
      1) A transaction goes in prepare in oplog application
      2) A user operation acquires a lock in mode S and then blocks on a prepare conflict with the prepared transaction.
      3) The commit of the prepared transaction attempts to reacquire (since the lock was yielded) an IX lock that conflicts with the mode S lock and blocks.

      Possible solutions:
      1) Do not yield locks for prepared transactions on secondaries.
      2) Say such a user operation is illegal. We do not think they can occur today.
      3) Yield locks in prepare conflicts

            judah.schvimer@mongodb.com Judah Schvimer
            judah.schvimer@mongodb.com Judah Schvimer
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