I will probably wrap it up in a blog post. But I have tried pg2, gproc, also stand-alone phoenix_pubsub. Then I found this gem:
it has some nice features, like sending message and collecting responses (multi_call), pub/sub and presence out of the box. Does seem to work great in clustered env, while I had real trouble getting gproc to work.
Gproc seems to depend on gen_leader which is not like one library but dozen of forks, forks of forks, and people would not agree which one is least buggy. This seems like a real mess, which is an indication to me to avoid the project at all.
