It would be useful to know how many threads are currently in the WiredTiger library doing (or attempting to do) work.

I believe this can be layered into the API entry macros. It would be nice to have this information at a finer grain as well - e.g: how many connection level API calls, how many session level API calls, how many cursor API calls.

Lets see how hard it is and whether the performance overhead of keeping the counters is worthwhile.