How to change the number of threads? Currently it is one for me:
julia> Threads.nthreads()
1
Is there a function/command line flag to add more threads? Is this documented somewhere?
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Set the JULIA_NUM_THREADS environment variable. See https://docs.julialang.org/en/stable/manual/parallel-computing/#Multi-Threading-(Experimental)-1 and https://docs.julialang.org/en/stable/manual/environment-variables/#JULIA_NUM_THREADS-1.
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In case anyone is searching for this, the correct links are now
https://docs.julialang.org/en/v1.0/manual/parallel-computing/#Multi-Threading-(Experimental)-1
and
https://docs.julialang.org/en/v1.0/manual/environment-variables/#JULIA_NUM_THREADS-1
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Any idea, if I’m using visual studio code (VS code), how do I set JULIA_NUM_THREADS=n before firing up julia?
I’ve tried changing settings to
“julia.executablePath”: “cd C:\Users\home\AppData\Local\Julia-1.0.3\bin\ & set JULIA_NUM_THREADS=20 & julia.exe”
but the command does not work like it would in command line.
Is there no way to spawn additional threads inside Julia itself? I’m developing a package that will support parallel processing, and I don’t want users to have to go in and change JULIA_NUM_THREADS manually.
7 Likes
I followed the instructions on the documentation page, but somehow the number of threads doesn´t change if I change the value of the environment variable JULIA_NUM_THREADS .
Does somebody has an idea why? Have I done something wrong?
In Juno. It works in the terminal REPL.
Juno has a set number of threads option in the Atom settings, which defaults to the number of cores. I don’t know exactly if it takes precedence over the environment-variable and if it gets the environment variable might depend on if you started it from a terminal or not.
But the safest should be to set the number of threads in the julia-client settings.
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Thanks a lot 