db.currentOp() will show us the currently-running operation in the database and will attempt to kill it. We need to run the use admin command before running killOp(). Needless to say, using killOp() against internal MongoDB operations is not recommended or advised, as the database may end up in an undefined state. The killOp() command can be used as follows:

> db.runCommand( { "killOp": 1, "op": <operationId> } )