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  1. Core Server
  2. SERVER-41037

Stepup should kill all user operations(that encounters prepare conflict) before taking RSTL lock in X.

    • Type: Icon: Task Task
    • Resolution: Fixed
    • Priority: Icon: Major - P3 Major - P3
    • 4.1.12
    • Affects Version/s: None
    • Component/s: Replication
    • Labels:
    • Fully Compatible
    • Repl 2019-05-20, Repl 2019-06-03

      Currently, there is a  3 way deadlock. Assume that we are transitioning from secondary to primary(signalDrainComplete).

      • Thread A (Read thread)  acquires RSTL lock in IX and  blocked by a prepared txn due to prepare conflict.
      • Stepup enqueues RSTL lock in X mode. And blocked behind A.
      • Prepared txn won’t be able commit until we are able to change our state to primary.


      Alternatively, thread A might have got blocked on prepare conflict due to conflicting DB/ collection lock. For eg. dbhash cmd. 

      EDIT: Blocked due to conflicting mongoDB locks  is not possible as secondary prepared txn yield mongoDB locks.

            pavithra.vetriselvan@mongodb.com Pavithra Vetriselvan
            suganthi.mani@mongodb.com Suganthi Mani
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