Why does setting ENV[JULIA_CPU_THREADS]=5 and ENV[JULIA_NUM_THREADS]=5 not affect nprocs() ? Here is what I get on startup:
julia> versioninfo()
Julia Version 1.3.1
Commit 2d5741174c (2019-12-30 21:36 UTC)
Platform Info:
OS: Linux (x86_64-pc-linux-gnu)
CPU: Intel(R) Core(TM) i5-9600K CPU @ 3.70GHz
WORD_SIZE: 64
LIBM: libopenlibm
LLVM: libLLVM-6.0.1 (ORCJIT, skylake)
Environment:
JULIA_CPU_THREADS = 5
JULIA_NUM_THREADS = 5
julia> nprocs()
1
So the environment variables are being set but the processes are not being allocated?
The reason is that threads aren't processes. There are different kinds of "parallelism". Processes are used for distributed (multi-core) computing, threads are used for multithreading (on a single machine/node). See the Parallel Computing section of the Julia documentation for more information.
To start Julia with multiple processes use the command line flag -p N, where N is the number of worker processes. Alternatively, you can addprocs to add processes programmatically in a script (like startup.jl).