I understood that Erlang hot patching was only at a function level, or some other limitation that required much care? No guarantees when the old code will be unloaded? It's been years and I only skimmed things so perhaps I'm wrong and should shut up. But anyways, nothing stops you from doing the same in other languages. Indeed, asp.net does this. But it's just a light perf hack - in general I'm unsure of the usefulness vs more robust approaches. Where do you find it beneficial? (Only time I desire such stuff is to hand off control of a socket to a new server version, and there's nonintrusive ways of doing that.)

I remember seeing someone porting OTP to Java or .Net. Again, what are the language level features that prevents this? Or is it more of a lack of a commercial entity to back the beginning of such a project? Personally, having to serialize everything and getting "transparent" scalability by moving stuff over the network doesn't appeal to me. I'm guessing the rest of the world just runs a cluster of HTTP servers or other middleware and leaves it at that.

Maybe I've just had a terrible exposure to Erlang. Users of it seem to enjoy it, but so do many users. The main point seems to be that Ericsson made a good switch with it... Which seems as fallacious as pointing out that Facebook used PHP.