Julia 1.0 Programming Cookbook

Multiple threads

Julia can be run in a multithreaded mode. This mode is achieved via the JULIA_NUM_THREADS system environment parameter. One should perform the following steps:

1. To start Julia with the number of threads equal to the number of cores in your machine, you have to set the environment variable JULIA_NUM_THREADS first
2. Check how many threads Julia is using with the Threads.nthreads() function

Running the preceding steps is handled differently on Linux and Windows.

Here is a list of steps to be followed:

1. If you are using bash on Linux, run the following commands:

$ export JULIA_NUM_THREADS=`nproc`$ julia -e "println(Threads.nthreads())"4$

2. If you are using cmd on Windows, run the following commands:

C:\> set JULIA_NUM_THREADS= ...