Launching with JULIA_NUM_THREADS=<max>

General Usage Performance
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1

Is there any drawback to always launching julia with the number of existing cpu cores?

Suppose my cpu has 4 cores, and I need to do some non-production stuff like debugging, etc:

# cpu with 4 cores
firefox &
export JULIA_NUM_THREADS=4 && julia
2 
leandro@pitico:~% julia -t auto
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.5.3 (2020-11-09)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

julia> Threads.nthreads()
8

julia>

A drawback? No, only your Julia will compete with the other processes of your computer.

1 Like
3

Actually there can julia can also compete with itself if one uses julia treads and BLAS, which by default has its own thread pool

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