Currently there's only a single idle timeout that applies to all connections and by default there's no timeout. Without a timeout then a burst in traffic will leave unnecessary connections around indefinitely. If you set a timeout then you cause unnecessary churn if your pool is already at the minimum size.

Could there be some way to define a dynamic idle timeout where its x if the pool is more than the minimum but if its already at the minimum then its y. Maybe allow a user-defined function to be set to define it based on some pool stats that get sent to the function?

What does the Mongo team recommend to solve these 2 issues?