ensure_started

[Bjorn Gustavsson]

"Vlad Dumitrescu (EAW)" <Vlad.Dumitrescu@REDACTED> writes:

> Hi,
> 
> I wonder about a thing. The following fun is an often used way to ensure that one uses "the one and only" server called ?MODULE.
> 
> ensure_started() ->
>     case whereis(?MODULE) of
> 	undefined ->
> 	    Pid = proc_lib:spawn(?MODULE, init, []),
> 	    register(?MODULE, Pid),
> 	    {ok, Pid};
> 	Pid ->
> 	    {ok, Pid}
>     end.
> 

A safer way is to move the call to register/2 into the init/0 function.

If two processes happens to start at almost the same time, the second
process will crash when calling register/2.

/Bjorn

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