[erlang-questions] Question about behaviours in Erlang/OTP

Tue Jul 15 01:20:41 CEST 2014

Hi Yves,

In the gen_server manual, in the Module:terminate/2 it states

If the gen_server is part of a supervision tree and is ordered by its supervisor to terminate, this function will be called with Reason=shutdown if the following conditions apply:
	* the gen_server has been set to trap exit signals, and
	* the shutdown strategy as defined in the supervisor’s child specification is an integer timeout value, not brutal_kill

So, if want to ensure that your gen_server terminate/2 function is call you need to trap exits.   This is most common if there is some amount of cleanup you want to make sure happens before the gen_server terminates.



On Jul 13, 2014, at 4:59 PM, Yves S. Garret <yoursurrogategod@REDACTED> wrote:

> Hello,
> I'm looking at some code that was written where a user uses a behaviour of gen_server and then uses a process_flag(trap_exit, true).  To me, this seems like a supervisor behaviour would work better.
> What would be a better approach in this case?  To declare this module a supervisor?  Is it possible (sensible? logical?) to give the same module gen_server and supervisor behaviours?
> Thanks in advance!
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