Why would one use
void *enif_alloc_resource(ErlNifResourceType* type, unsigned size)
as opposed to
void *enif_alloc(size_t size)
when trying to allocate memory from an Erlang C NIF?
Reference does not specify much as to why.
enif_alloc_resource is used to create resources which are garbage collected by the vm when not used any more. enif_alloc works just like malloc, only is uses an Erlang VM specific implementation rather than the OSs malloc. Take a look at the documentation for ErlNifResourceType and the functions which use it for some more details.
来源：https://stackoverflow.com/questions/14420970/allocating-memory-in-erlang-c-nif