[erlang-questions] erlang process schedule

Jan Lehnardt <>
Mon Jan 19 16:19:30 CET 2009


On 19 Jan 2009, at 03:35, Kaiduan Xie wrote:

> Hi,
>
> Can anyone give a systematic view on how erlang schedules process?  
> Joe's "Programming Erlang" gives details on how fast an erlang  
> process is created/destroyed; unfortunately it does not elaborate  
> how erlang process is scheduled, and how fast is the process switch.  
> (We all konw thread context switch in C/Java is not cheap)

Processes run for a fixed number of "reductions" until they cat  
stopped and the next one gets executed. This happens round-robin.  
There is one optimisation that when a process sends a message to  
another one, the sending process gets stopped and the remaining  
reductions go to the called process. Switching processes is as fast as  
increasing a pointer in the array that keeps track of all processes.

Cheers
Jan
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