[erlang-questions] supervisor woes

Adam Kocoloski <>
Wed Sep 8 20:59:22 CEST 2010


On Sep 8, 2010, at 11:36 AM, Jared Nance wrote:

> Hello List-
> Thanks in advance for whatever help you can offer.  I'm putting together a supervision tree which is rather simple - at the moment, there is a supervisor that manages several other supervisors, and those supervisors each manage only worker nodes.  The problem I am having is with one of my supervisors which manages 4 worker nodes.  Each node is a gen_server that uses the same callback module, but with different arguments to start_link.  The childspec for the worker nodes looks like
> 
> {cardA, {ios_faux_card, start_link, [cardA]}, permanent, brutal_kill, worker, [ios_faux_card]}
> 
> and so the supervisor for these workers is started with a child spec that looks like
> 
> {{one_for_one, 5, 10}, [{ios_card_super, {ios_card_super, start_link, [{cardA, {ios_faux_card, start_link, [cardA]}, permanent, brutal_kill, worker, [ios_faux_card]}], permanent, infinity, supervisor, [ios_card_super]}
> 
> and that works just fine.  the problem arises when i try to add a second (or third, or fourth) gen_server to the list of processes that the ios_card_super is supervising.  if i try starting it with this child spec instead:
> 
> {{one_for_one, 5, 10}, [{ios_card_super, {ios_card_super, start_link, [{cardA, {ios_faux_card, start_link, [cardA]}, permanent, brutal_kill, worker, [ios_faux_card]},{cardB,{ios_faux_card, start_link, [cardB]}, permanent, brutal_kill, worker, [ios_faux_card]}], permanent, infinity, supervisor, [ios_card_super]}
> 
> it refuses to start.  what's more, the only response I get out of it is {error, shutdown}.  I have put io:format debug statements in the ios_faux_card module and it's clear that start_link/1is never being called when there are 2+ workers to supervise.
> 
> Thanks for whatever help you can offer on this very frustrating issue.
> 
> Jared N

Hi Jared, you wouldn't happen to be trying to register the process in ios_faux_card, would you?

Adam




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