I posted a showdown of various open source servers that can be run on heroku a few days ago, including puma, which some people interested in this may be interested in:

https://github.com/jrochkind/fake_work_app/blob/master/READM...

For some reason it didn't get much HN traction. But either it inspired these recent HN posts involving puma, or it's just a coincidence -- either way I'm glad to see puma getting more attention.

I think multi-threaded request dispatch (from either puma or passenger enterprise) are often the best way to maximize throughput in a web server with I/O-bound work, as the Java community has been doing for a while. Any implementation details are just minor tweaks compared to just doing multi-threaded concurrent request dispatch in the first place -- so it's no surprise to see Passenger Enterprise and puma performing similarly.

i agree with the Phusion essay, that Passenger currently has more robust admin/management/supervision features than puma. I hope puma continues to evolve, inspired by passenger

Although these features are not trivial to implement well -- I am very impresed by passenger's feature set, and very robust and reliable performance.

But if you want a free/open-source solution, or a solution that it makes sense to run on heroku -- puma is a (and the only) solid concurrent-request-dispatch solution already.