So you feel your program is better off for having only one connection pool and being unable to use another? Regarding caching your processor tends to feel othe

So you feel your program is better off for having only one connection pool and being unable to use another? Regarding caching your processor tends to feel otherwise and has multiple levels of cache because globally mutating state in a coherent way is slow as molasses. I can't wait to hear what awesome program needs a connection pool and access to the JIT at the same time. Are you writing a SQL compiler that sends mail? Is your awesome program by any chance written in JavaScript or PHP? PS. Databases aren't really global mutable state as in when you ask your database for a count of rows in a table the answer you get back won't ever change because magic. Also, because of the ways database ARE global mutable state you run into all the issues you typically do with global mutable state. And then the places you do have global mutable state turn into performance nightmares. (Read: Hot spots)