[erlang-questions] Synchronous way to handle timeout between gen_server(s)

Arun Muralidharan <>
Tue Oct 22 13:22:22 CEST 2013


Not 100% sure, but you can catch the timeout with handle_info.
Somethig like
handle_info(timeout, State)->
  # do something .

-Arun


On Tue, Oct 22, 2013 at 4:16 PM, Attila Rajmund Nohl <
> wrote:

> Hello!
>
> Exactly what would you like to achieve? If you don't expect serv2 to
> freeze, you can set the timeouts in the gen_server:calls to infinity.
>
> 2013/10/22 Tien Le <>:
> > Hi,
> >
> > Please look at my sample code below. I have 2 gen_servers (serv1 and
> serv2).
> > serv1 start_link serv2, and traps exit.
> >
> > %%% serv1:do/0 implementation: %%%
> > do() ->
> >     gen_server:call(serv1, do).
> >
> > handle_call(do, _From, State) ->
> >     Result = serv2:do(),
> >     {reply, Result, State}.
> >
> >
> > %%% serv2:do/0 implementation: %%%
> > do() ->
> >     gen_server:call(serv2, do).
> >
> > handle_call(do, _From, State) ->
> >     %% Something that takes time like timer:sleep/1
> >     Result = timer:sleep(5000),
> >     {reply, Result, State}.
> >
> >
> > As you can see that serv1's gen_server:call and serv2's gen_server:call
> have
> > the same timeout value (5000ms by default).
> >
> > When I call serv1:do().
> > serv1 always terminates first due to timed out:
> >
> > =CRASH REPORT==== 22-Oct-2013::10:26:38 ===
> >   crasher:
> >     initial call: serv1:init/1
> >     pid: <0.43.0>
> >     registered_name: serv1
> >     exception exit: {timeout,{gen_server,call,[serv2,do]}}
> >       in function  gen_server:terminate/6 (gen_server.erl, line 747)
> > ...
> >
> > One workaround is to increase the timeout of serv1 and serv2
> > gen_server:call/3, like this:
> > gen_server:call(serv1, do, 5020) => gen_server:call(serv2, do, 5010) =>
> > timer:sleep(5000)
> >
> > I would like to ask you if there's any nicer and synchronous way to
> handle
> > the timeout in this case?
> >
> >
> >
> > _______________________________________________
> > erlang-questions mailing list
> > 
> > http://erlang.org/mailman/listinfo/erlang-questions
> >
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> 
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