[erlang-questions] gen_server cast question

Ladislav Lenart <>
Wed Jan 31 18:46:32 CET 2007


Ulf Wiger wrote:
> Den 2007-01-31 17:20:33 skrev Logan, Martin <>:
> 
>> Message order is not guaranteed with asynchronous messaging in any case.
>> You should never rely on it.  Also, as an aside, it would be strange to
>> have a reference to a process for a node that is not connected, that
>> suggests poor design.
> 
> In Barklund's formal semantics for Erlang
> (http://citeseer.ist.psu.edu/fredlund01framework.html)
> 
> the following is stated:
> 
> "The semantics communication (rule com) is such that if two consecutive 
> messages m1 and m2 are sent by process p1 to process
> p2 then message m1 will always arrive before message m2."
> 
> I'm not sure where else it is defined, but I'm pretty sure that you can 
> rely on this being true.
I also think that the order is guaranteed (between two processes that is):

   [from Concurrent Programming in Erlang, page 69]
   Messages are always delivered to the recipient,
   and always in the same order they were sent.

But then I think that presence of spawn in do_send breaks this "rule"...

Ladislav Lenart




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