Engineering Ticket Description:
It would be nice if users could configure a outbound connection pools in a way as most of the drivers work. The use case is to do throttling of the amount of connections that hit the shards on the mongos level - e.g. if a number of requestes/active connections to mongos exceeds the specified threshold, some connections will have to wait for their turn to be served.
Implementing this would mean that we need to expose the standard connection pool-related options such as:
Given that mongos is based on a C++ driver I presume that should be doable.
To clarify, this commit exposes the connection pooling options that currently exist in mongos, rather than driver equivalent options.
Added knobs include: