Double lock

May result in immediate deadlock. Attempt to acquire a non-recursive lock that is already held
/src/mongo/db/default_baton.cpp:212: LOCK 148927 "unique_lock" locks "this->this->_mutex". [Note: The source code implementation of the function has been overridden by a builtin model.]
/src/mongo/db/default_baton.cpp:212: LOCK 148927 "lk" and "this->this->_mutex" point to the same lock. [Note: The source code implementation of the function has been overridden by a builtin model.]