libfringe VS crossbeam

There’s a bunch of library-based implementations of coroutines for rust. I recall https://github.com/edef1c/libfringe being the most interesting one, but it is quite dated. I don’t think there’s a lot of community interest in stackfull coroutines at this point.

As we saw earlier, scheduling threads is a hard task for the operating system. To replace one thread that's being executed with another one, a lot of work needs to be done (including saving all the registers and some thread state). However, switching between Lunatic Processes does only the minimal amount of work possible. With an idea pioneered by the libfringe library and using some asm! macro magic, Lunatic lets the Rust compiler figure out the minimal number of registers to be preserved during context switches. This makes scheduling Lunatic processes zero-cost. On my machine usually 1ns, equivalent to a function call.

One very common queue implementation you can use to implement actors is the crossbeam-deque. It's work-stealing in nature, works in multi-threaded environments and has no locks. The implementation is quite simple to follow:

https://github.com/crossbeam-rs/crossbeam/blob/master/crossb...

Sure! However, the work-stealing queue in rayon [1] uses three atomic operations instead of the two atomic operations for a mutex for a global lock. The difference, however, is the three atomic operations for the thread-local queue should be uncontended, whereas a global lock on a global work queue would experience contention from every thread trying to access it for jobs.

Between the choices of "single work sharing queue with a big mutex on it that all threads access for work" vs "per-thread work-stealing queue that's uncontended for the cost of one extra atomic," in what situations would the work-sharing queue with the global mutex outperform? Perhaps if there's a small number of jobs, and there's not enough time for the work-stealing algorithm to distribute jobs to the worker threads before the work-sharing algorithm has already finished.

[1]: https://github.com/crossbeam-rs/crossbeam/blob/423e46fe20471...

Crossbeam isn't async[0]. It can multiplex with itself (via the `select!` macro), but not with anything else.

[0]: https://github.com/crossbeam-rs/crossbeam/issues/896

Shooting from the hip, crossbeam might be a good candidate for understanding the thread safety aspects of Rust. I kind of feel like this is probably "too big" of a project if you're just learning, but I can't think of something smaller off the top of my head that would be suitable.

I am familiar with crossbeam channels, but now I need to work with python, and I was looking for a similar library.

In the C++ example you create a naive mpsc queue using a std queue and a mutex, while in the rust example you use `std::sync::mpsc` which is now implemented internally using https://github.com/crossbeam-rs/crossbeam .

There are more in the ecosystem like in https://crates.io/crates/crossbeam

The crossbeam crate offers a powerful alternative to standard channels with support for the Select operation, timeouts, and more.

From this project: https://github.com/crossbeam-rs/crossbeam