Currently

• the limit on the number of connections is determined by the number of available file descriptors, and we fail gracefully by refusing additional connections if this limit is exceeded
• whereas the limit on the number of WT sessions is hard-coded at 20000, and we abort if this limit is exceed.

Each connection will require a WT session to do anything useful. So this means that if the maximum number of connections is < 20000 we fail gracefully when this number is exceeded, whereas if the maximum number of connections is > 20000 we may abort when we exceed 20000 connections.

We should either make maximum number of sessions track maximum number of connections, or hard code the maximum number of connections as well.