FusionReactor allows you to see the different MongoDB transactions run by your application, as children of the top level WebRequests or split between views of the different transaction types: i.e. find, findOne, update, aggregate, mapReduce, insert etc. FusionReactor will show you the time taken by each operation and the arguments/parameters passed to it.
Visualize MongoDB transactions in real-time. FusionReactor shows you Time and Activity graphs for the different MongoDB transaction types. These graphs give a valuable insight into how MongoDB is performing for you. Use this data to focus efforts at performance tuning the right transactions.
See Exceptions that are thrown from the MongoDB Java driver. These are displayed within the details of the individual transactions. The exact exception thrown and the exception stack trace allow you to drill down and find the cause of the problems you may be having.