parallel-processingjuliacpu-cores

Obtain the number of CPU cores in Julia

I want to obtain the number of cores available in Julia. Currently I am doing the following:

using PyCall
@pyimport psutil
nCores = psutil.cpu_count()

This calls a Python function. I would like, however, to use some Julia procedure. How can it be done?

Solution

  • I'm not 100% certain about this, but CPU_CORES returns the number of (hyper-threading) cores on my machine (OSX 10.9.5 and Julia 0.3.5), even when I start Julia in serial mode. I've been checking the number of available cores using nworkers() and nprocs(). Starting up Julia without the -p flag this returns 1 for both.

    When I start julia as julia -p 4

    julia> nprocs()
5

julia> nworkers()
4

    In both cases CPU_CORES returns 8.