Erlang on multicore CPU

Question

I am learning erlang and am quite impressed how easy it is to parallelize work. To practice a bit I dug up the good ole Fibanocci sequence. In the following code I try to ta

Answer 1

The reason you see so little parallelism is that your program is basically sequential. All the work is being done in one process in the fib/3 function. The processes you spawn all just send a message and then die and the spawning process synchronously waits for these messages so there is no real concurrency. You could just as well just call the loop/3 function directly with these values.

Otherwise it is as others have mentioned that Erlang automatically uses all the multiple cores available and distributes processes across these where possible. In your case however there is little need to do this and no gain so the system does not do it.

This is actually one of the more difficult things in writing concurrent applications. It is not enough to just spread things into many processes, you actually have to make sure that these processes actually run concurrently. It means rethinking your algorithms, which can be difficult.