> And that said, implementing a super-fast setcontext/swapcontext is like twenty lines of assembly with not too many gotchas, if you don't care about saving a f

> And that said, implementing a super-fast setcontext/swapcontext is like twenty lines of assembly with not too many gotchas, if you don't care about saving a few things that require syscalls. sigaltstack(2) wasn't all that prohibitive when I did that in Python 2.6 back then. Was it 2009? I seriously can't understand this obsession with FSMs. A naive setcontext()-based implementation outperfomed both greenlets (with its crazy legacy of memcpy-ing parts of stack from stackless) and Tornado/Twisted (with them being pure-python and therefore lacking any means to force some async on client libraries. which one does in C) while letting everyone write some nice clean synchronous-looking code. 10 years later we end up with half a language hacked up and still nowhere near the ease of use that was coded in a week or so.