Erlang Supervisor Behavior Gotcha – Worker Init Params
When starting up a behavior like supervisor, the start_link func looks something like:
start_link() ->
supervisor:start_link({local, ?MODULE}, ?MODULE, []).
Which in turn calls the initialization callback:
init(_Args) -> %% do some stuff.
Notice that the initialization callback takes 1 argument event though the params list (the third parameter) is empty in your start_link func.
So, naturally (am I alone in this?) I assumed that when defining a Child Spec for a Supervisor, the {M, F, A} definition would follow the same pattern:
Childspec = {child1,
{child1, start, []},
permanent, brutal_kill, worker, dynamic},
%% ...
But the above definition does not call child1:start/1, where the one parameter is the emtpy list. Instead, the list items are extracted as individual parameters. So {child1, start, [p1, p2, p3]} would call child1:start/3, and {child1, start, []} calls child1:start/0. Just something to look out for if you’re new to erlang and the supervisor behavior like me.
Calum is discussing. 
nulls102, and 
jamesonh are discussing. 
venkat2009 are discussing. 
Naked Bunny with a Whip 7:30 pm on August 9, 2010 Permalink
Holy crap, that's been biting me in the butt all afternoon. Thanks for taking a load off my mind!
Double Jogging Stroller 3:33 am on March 4, 2011 Permalink
Excellent! Great article, I already saved it to my favourite,