Explaining Ruby Fibers | Hacker News Reader

Explaining Ruby Fibers

noteflakes.com

169 pointstekkertje13 comments

This was a great read, but even more interesting was all the work on the author’s GitHub:

Sharon is essentially developing a whole new stack of Ruby core libraries updated to feel more 2021 web than 2006 web (but in a good way). There’s a lot of neat stuff here to explore.

An algebraic effects library: https://github.com/digital-fabric/affect

He has great taste!

I'm a he. No offense taken, thanks for the kind words!

Fixed, my apologies

I think it is unfortunate that whole stack gets zero attention.

Does anyone know of if the issues brought up by njs in this thread still apply? https://trio.discourse.group/t/structured-concurrency-in-rub...

Have to admit, clicked on this expecting to learn about some sort of exotic optical fiber.

Just for the note, in JS these two:

   async function foo() {...} 
   function* bar() {...} // a.k.a. generator

are fibers. These are execution contexts that JS VM can be switched into. The first one (asynchronous function) uses kind-of preemptive multitasking (implicit context switch) and generators are closer to canonical fibers - cooperative multitasking with explicit yield of VM to other fibers.

Async functions and generators, in both JavaScript and Python, are forms of (asymmetric) stackless coroutines. Usually the term “fiber” is only used for stackful coroutines.

Fibers are symmetrical coroutines, generators and async functions are asymmetrical coroutines. They are slightly different.

How do the fibers being introduced in PHP 8.1 compare with Ruby's?

https://php.watch/versions/8.1/fibers

Looks like they work the same way. The documentation talks about the same concepts: cooperatively-scheduled tasks implemented in the virtual machine with small stacks that support concurrency, don't run code in parallel and may perform I/O asynchronously in parallel given operating system support. Implementation details will vary.

PHP’s fibers seem to be purely asymmetric - they provide only `resume(fiber)` and `suspend()` functions. Lua’s coroutines are similar.

OTOH Ruby’s fibers also provide a symmetric `transfer(fiber)` function. Asymmetric and symmetric coroutines are equivalent, so presumably Ruby implements one in terms of the other - it would be interesting to find out exactly how that was done.

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