Data race condition

The value of the shared data will be determined by the interleaving of thread execution. Thread shared data is accessed without holding an appropriate lock, possibly causing a race condition
/src/mongo/db/repl/bgsync.cpp:966: MISSING_LOCK 150277 Accessing "this->_lastOpTimeFetched" without holding lock "mongo::repl::BackgroundSync._mutex". Elsewhere, "mongo::repl::BackgroundSync._lastOpTimeFetched" is written to with "BackgroundSync._mutex" held 2 out of 3 times.