[erlang-questions] supervisor woes

Jared Nance <>
Thu Sep 9 00:17:33 CEST 2010


solved.

Basically I hadn't realized that if in the child spec, the argument to child:start_link was a list of length N, child:start_link/N would be called.  This resulted in {'EXIT', undef, {....}} coming back at me once I had sasl running, and helped me track it down to this.  

Thanks for all the help.
JN

On Sep 8, 2010, at 1:43 PM, Anthony Molinaro wrote:

> 
> What does the child spec for the supervisor calling your supervisor look like?
> Maybe you are calling your supervisor a worker in that spec?
> 
> -Anthony
> 
> On Wed, Sep 08, 2010 at 01:21:27PM -0700, Jared Nance wrote:
>> Also, as a point of clarification:  If I start the ios_card_super manually with the multiple children, it works without a hitch - all of the ios_faux_cards get registered correctly and behave normally.  It's only when I try to start the ios_card_super as a supervised node in a supervision tree that I have the problem.
>> 
>> On Sep 8, 2010, at 11:59 AM, Adam Kocoloski wrote:
>> 
>>> 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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> -- 
> ------------------------------------------------------------------------
> Anthony Molinaro                           <>



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