Comment made by: mpenet
Thanks for the feedback, but I don't think you read my patch correctly.
I do not change the case you mention (promise), the only thing that's changed is that for the few cases where clojure.core.async.impl.dispatch/run is called, meaning the function is run in a globally defined threadpool used by everything in core.async with the exception of thread, it can ***optionally be done via a function argument supplied threadpool. The default is unchanged, if you don't pass an executor you get the current master core.async behavior without any change at all.
Few people mentioned that need, some publicly, some in private, myself included, and I know of a team who expressed the same concerns and just switched one of their systems from core.async to manifold because the latter offer more knobs of that sort.
In the end it's about control, it changes nothing to core.async and it's current execution model if you don't care about it, but it's important to people who needs that kind of fine grained tuning.
It came up again a couple of days ago on twitter: https://twitter.com/puredanger/status/576378306062262272 and you could certainly find reference of it in the irc logs as well.
I would have released this as a lib if that was possible, but the code implicated is sometimes very deeply rooted and make it nearly impossible to do without forking the whole library, hence that patch.