How does Project Loom Fibers/Green threads help in Anyway ?

[David Holmes]

Project Loom is still being set up and should have a project page and 
mailing list soon.

David

On 10/01/2018 11:58 PM, kant kodali wrote:
> Hi All,
> 
> I came across the links below and I wondering how Fibers can really help ?
> when compared to using a thread pool (which is a pool of kernel threads)?
> Sure having both options is great but I am trying to understand what
> difference can it make in terms of performance ?
> 
> Here is what I know
> 
> 1) Kernel threads are expensive and the default stack size is in MB's
> whereas Fibers can have a small stack size somewhere in KB's so one can
> create as many of them. so what? eventually they all have to map to Kernel
> threads and thread pool exists so user don't create as many as say Fibers.
> isn't it?
> 
> 2) Fibers have no idea about kernal threads and vice-versa. so if a Fiber
> makes a blocking system call it has not idea that the kernel thread is
> blocked and there is no upcall mechanism by any major OS.
> 
> 3) One can argue Fibers are great when a program is making lot of async
> calls but I wonder how this is any better in terms of performance when
> compared to having small thread pool that makes async calls?
> 
> If this is all about expressing something gets easier in Fibers than using
> thread pool but there is no performance difference then I must say this is
> just subjective so everyone can have their own opinion.
> 
> At this time, I am not seeing how Fibers can be better performant than
> having a pool of Kernel threads? if they are in some cases can someone
> please provide any examples so I can enlightened?
> 
> 
> 
> http://cr.openjdk.java.net/~rpressler/loom/Loom-Proposal.html
> https://hn.svelte.technology/item/15599854
>