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  1. Core Server
  2. SERVER-32284

awaitReplication can hang when the optime to wait for does not match the minSnapshot.

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    • Repl 2018-01-01, Repl 2018-01-15, Repl 2018-01-29
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      ReplicationCoordinatorImpl::_awaitReplication_inlock accepts waiting for an opTime and a minSnapshot. This method will register itself onto a waiter list for a condition notification and successfully return when _doneWaitingForReplication_inlock returns true.

      In order for the predicate to return true, a valid snapshot must exist at the minSnapshot time.

      However, the condition variable is notified when _doneWaitingForReplication_inlock succeeds with a trivially true minSnapshot value. Also note that notifying a waiter also removes it from the list waiters that are notified when optimes advance.

      In this case, the predicate for _awaitReplication_inlock is stronger than to be notified, and because notification happens at most once, a client can hang waiting for a followup notification will never come.

            Assignee:
            benety.goh@mongodb.com Benety Goh
            Reporter:
            daniel.gottlieb@mongodb.com Daniel Gottlieb (Inactive)
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