Hacker News Reader

Comment by gmadsen | Hacker News Reader

I know c++ has a lack luster implementation, but do coroutines and channels solve some of these complaints? although not inherently multithreaded, many things shouldn't be multithreaded , just paused. and channels insteaded of shared memory can control order

View on HN

Coroutines basically make the same observation as transmit windows in TCP/IP: you don’t send data as fast as you can if the other end can’t process it, but also if you send one at a time then you’re going to be twiddling your fingers an awful lot. So you send ten, or twenty, and you wait for signs of progress before you send more.

On coroutines it’s not the network but the L1 cache. You’re better off running a function a dozen times and then running another than running each in turn.

fair enough, that was the design choice c++ went with to not break ABI and have moveable coroutine handles

rust accepted the tradeoff and can do pure stack async,

there are things you can do in c++ to not get the dynamic allocation to heap, but it requires a custom allocator + predefining size of coroutines.

https://pigweed.dev/docs/blog/05-coroutines.html

I've found both explicit future/promise management and coroutines difficult (even irritating) to reason about. Co-routines look simpler at the surface (than explicit future chaining), and so their the syntax is less atrocious, but there are nasty traps. For example:

https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines...

Reply on news.ycombinator.com