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

[David Holmes]

http://mail.openjdk.java.net/mailman/listinfo/loom-dev

David

On 13/01/2018 8:05 PM, David Holmes wrote:
> 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
>>