[erlang-questions] Timeouted gen_server:call

[Bernard Duggan]

On 13/05/10 00:48, Dmitry Belyaev wrote:
> I have a gen_server and many clients. Clients send request to the server
> with gen_server:call(Server, Msg, Timeout) and when timeout occurs they
> ask server to abort appropriate reply. But server may reply right before
> it receives abort message and I may get trash in client's mailbox.
>
> I'm not sure that client can throw away this trash itself. So it is
> possible for client to fill his message queue with lots of such messages.
>    
Why can't the client clean up its queue itself?  A general rule of 
thumb, in my experience at least, is that processes should flush their 
message queue of any "unexpected" messages - if not all the time, at 
least regularly.  Not because they /should/ expect to get them, but 
because you don't want them to misbehave if they do (you're right to be 
concerned about a growing queue - as several people on this list, myself 
included, have discovered it can be "bad" when a queue gets too big).  
In the case of a gen_server and similar, this is easy - just add a 
catch-all

handle_info(_, State) -> {noreply, State}

In the case of non "gen style" code, just make sure it regularly reaches 
and loops on a 'receive' block which has a clause which matches 
everything you're not interested in and discards it.

Cheers,

Bernard