[cjfd]

The thing I would worry about here is that perhaps not all of your tasks have the same performance demands. There may be tasks related to RPC that should run as quickly as possible and tasks related to computation that could take a long time. If all of the threads in the threadpool are busy with an expensive computation there could not be left any to quickly handle RPC requests.

I personally prefer to do as much as possible just in one thread, where you can run things asynchronously with a single threaded message loop and then have a thread pool next to that for expensive computations. This also tends to reduce the number of things that need to be protected with a mutex.