I am curious, when OCaml multicore is finished and merged mainstream, will programs written with Async and Lwt (or similar) libraries become multithreaded automatically? Will it require major changes in Lwt and Async libraries? Or is it totally impossible and will require rewriting programs themselv…

It will require rewriting programs. Right now, Async programs at least rely on the fact that they can mutate state in a region between binds without fear of interruption. This would simply not be true if the Async scheduler automatically just scheduled jobs on different cores. We’ve thought a bit a…

We’re currently designing an entirely new multicore IO library based on effects, that should support high-performance direct-style I/O. I anticipate (subject to the emerging design) that there will be some manual migration path between this library and existing monadic concurrency libraries. But no…

I can probably write an auto parallelizing compiler for this. At least, it’d be nice to do some basic profiling to find the hot blocks, and try to unroll loops, etc. Like some basic passes of an auto parallelizing compiler. The hard part is the memory distribution stuff, that’s a little difficult, I…

I can probably write an auto parallelizing compiler for this. :laughing: Famous last words.

Haha yeah, I was thinking I should have said I wouldn’t do it for free, though. :stuck_out_tongue: :joy:

More seriously, I think the advances are really exciting here, I would love to try an explicit parallel programming alternative to Haskell for multicore programming. It’s unfortunate that some semantics will be broken but it sounds like that’s a necessary evil. Multicore reagents, algebraic effects,…

Pardon the necromancing of this old thread. As per @yminsky, I understand why Async programs would require rewriting to take advantage of parallelization, to maintain its guarantee that it won’t interrupt between binds. But Lwt doesn’t provide this guarantee, so, shouldn’t it be possible to simpl…

I’d suspect that spawning a new fiber for every lwt bind (or equivalent), which could then potentially execute on another domain, would be too expensive, but I might be wrong.

Lwt is the same way. Since lwt has no preemptive multithreading available, there’s no way to stop a computation from happening and switching to another thread unless the thread happens to be calling an lwt function of some sort (usually bind). This is a very good thing. If you had to handle preempti…

@bluddy I call your attention to @rgrinberg ’s article on the differences between them, here Abandoning Async Quote async >>= f schedules the computation f using the value of async once it’s determined. However, there’s a slight twist in each library. Lwt - if async is already determined when b…

Multicore, Async, and Lwt

Ecosystem

XVilka September 15, 2023, 9:08am 18

A simple porting guide from Lwt to Eio as a definitive answer to my own question from years ago: GitHub - ocaml-multicore/lwt_eio: Use Lwt libraries from within Eio

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Multicore, Async, and Lwt

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