Rob Pike – 'Concurrency Is Not Parallelism' [video] (2012)

Post by bjoli » Sun, Jul 05, 2026, 5:46 AM UTC

kllrnohj wrote: post #27

bjoli wrote: post #23

It seems like we forgot about lightweight fibers for about 30 years and then collectively rediscovered it in about 2010. sure, Java did green threads, but not like m:n stuff. I sometimes wonder where we would be now if people would have gone "Wow, mr Reppy! concurrentML is so cool!" in 1993. instead we got pthreads and collective amnesia and later we got go's girly times and channels which are only half way there.

That's because they are very rarely useful. This was true then and it's still true now. There's just not many workloads where it makes sense to need to rapidly launch a thread that doesn't need to do much of anything but does need to exist for a while before terminating. What is useful is the state machine aspects of things like coroutines or async/await, but those aren't quite fibers and very much aren't M:N threadi…

Post by kllrnohj » Sun, Jul 05, 2026, 7:23 PM UTC

bjoli wrote: post #42

kllrnohj wrote: post #27

Earlier quoted context omitted.

That's because they are very rarely useful. This was true then and it's still true now. There's just not many workloads where it makes sense to need to rapidly launch a thread that doesn't need to do much of anything but does need to exist for a while before terminating. What is useful is the state machine aspects of things like coroutines or async/await, but those aren't quite fibers and very much aren't M:N threadi…

you can implent something like futures on top of cml and use it as async. then you get async for stuff where async is useful and a proper way to write parallel programs for when async would lead to all the bad stuff async leads to. i rarely write gui stuff and I find async is rarely what I need. in f# I at least have the option to use hopac.