The future of concurrent programming

[eao197]

On Wed, 30 May 2007 18:01:26 +0400, Sean Kelly <sean at f4.ca> wrote:

>>  Erlang's threads are better than fibers because they are pre-emptive.  
>> However, this is only possible because Erlang runs on a VM.  
>> Context-switching in the VM is much cheaper than in the CPU (ironically  
>> enough), which means that D isn't going to get near Erlang's threads  
>> except on a VM that supports it (somehow I doubt the JVM or CLR come  
>> close).
>>  Fibers are nice when you don't need pre-emption, but having to think  
>> about pre-emption makes the parallelism intrude on your  
>> problem-solving, which is what we would like to avoid.
>
> If I understand you correctly, I don't think either are a clear win.  
> Preemptive multithreading, be it in a single kernel thread or in  
> multiple kernel threads, require mutexes to protect shared data.  
> Cooperative multithreading does not, but requires explicit yielding  
> instead.  So it's mostly a choice between deadlocks and starvation.

AFAIK, there isn't shared data in Erlang -- processes in Erlang VM  
(threads in D) communicate each to another by sending and receiving  
messages. And message passing mechanism is very efficient in Erlang VM.

-- 
Regards,
Yauheni Akhotnikau