Potential problems I'm aware of:

1. Errors while connecting/sending are not handled. I thing this is a
   good thing to catch problems early on but I might be wrong.

2. If connection to any resolver server fails, all connections in given
   worker are closed and reinitialized.

3. Logging and postprocessing is missing. I.e. there is not way to
   distinguish connection reset from timeout for given query.