Each process just return it's own pid when performing lookup_pids

[hamdijmii1992]

I tried to regsiter some processes with a famliy name with gproc.
For this reason I created a gen_server that contain two function, the first one is to
handle registration and the second one is to lookup Pids of registered processes.
After that, I opnened two erlang consoles and I registered two processes with the same property
(each console request the server to register one process)
My server code is as follows:

`start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [],[]).

init([]) -> gproc:start_link(), {ok, []}.
%% Synchronous call
register(Pid, Name) ->
gen_server:call(Pid, {register, Name}).

getpids(Pid, Name) ->
gen_server:call(Pid, {getpids, Name}).

handle_call({register, Name}, _From, State) ->
gproc:reg_or_locate({p,l,Name}),
{reply, Name, State};

handle_call({getpids, Name}, _From, State) ->
Pids = gproc:lookup_pids({p,l,Name}),
{reply, Pids, State}.

handle_info(Msg, State) ->
io:format("Unexpected message: pn",[Msg]),
{noreply, State}.

terminate(normal, State) ->
ok.`

I registered my processes with
server_name:register(PID,<<"test">>)
and I lookup the pids with:
server_name:getpids(PID,<<"test">>)

But when I tried to get the pids of my family processes (Basically I have to pull a list
with 2 pids) I got just one pid (each console just lookup the pid registered by him self
and not render the pid registered with the other console).

Thanks for your help.
Best Regards.

[tahteche]

Have not tested your code yet but from what I see you are registering locally and doing lookups locally because of the l in gproc:reg_or_locate({p,l,Name}), and Pids = gproc:lookup_pids({p,l,Name}),. This means your properties are registered just within each node (the two consoles in your case I guess).

Try doing a global registration and lookup using g in place of l that is {p,l,Name} should be {p,g,Name}

[uwiger]

The function gproc:reg_or_locate/1 is only intended for unique names, and should crash if called with a (non-unique) property:

Eshell V7.3.1  (abort with ^G)
1> application:ensure_started(gproc).
ok
2> gproc:reg_or_locate({p,l,foo}).
** exception error: bad argument
     in function  gproc:reg_or_locate/1
        called as gproc:reg_or_locate({p,l,foo})

If you know that you'll only register a name once, you can use gproc:reg/1. If you want the call to be tolerate repeated registrations of the same name, gproc:ensure_reg/1 works nicely:

3> gproc:ensure_reg({p,l,foo}).
new
4> gproc:ensure_reg({p,l,foo}).
updated