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/oplog_buffer_blocking_queue.cpp:83: MISSING_LOCK 141354 Accessing "this->_isShutdown" without holding lock "mongo::repl::OplogBufferBlockingQueue._mutex". Elsewhere, "mongo::repl::OplogBufferBlockingQueue._isShutdown" is written to with "OplogBufferBlockingQueue._mutex" held 1 out of 1 times (1 of these accesses strongly imply that it is necessary).