Let's write a setjmp

Re:Let's write a setjmp by lstodd on Sunday February 12, 2023 @04:07PM (#34766962)

> 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.

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Re:Let's write a setjmp by duped on Monday February 13, 2023 @10:16AM (#34774422)

> I seriously can't understand this obsession with FSM

It's the most optimal representation of the common-case (non-recursive asynchronous tasks), has the same overhead as a function call, plays very well with branch prediction, can be easily inlined by optimizers, and it's a lot easier to implement.

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