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Bug 784245 - dev-lang/julia-1.6.0 fails to work with OMP_NUM_THREADS whereas dev-lang/julia-bin-1.6.0 does
Summary: dev-lang/julia-1.6.0 fails to work with OMP_NUM_THREADS whereas dev-lang/juli...
Status: UNCONFIRMED
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: Current packages (show other bugs)
Hardware: AMD64 Linux
: Normal major (vote)
Assignee: Gentoo Science Related Packages
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Reported: 2021-04-19 20:42 UTC by Paul Preney
Modified: 2021-04-19 23:36 UTC (History)
5 users (show)

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Runtime testing required: ---


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Description Paul Preney 2021-04-19 20:42:26 UTC
dev-lang/julia-1.6.0 fails to work with OMP_NUM_THREADS (nothing happens at all) built with USE=system-llvm and without.

dev-lang/julia-bin-1.6.0 does work with OMP_NUM_THREADS properly.

It doesn't matter what eselect blas and/or eselect lapack is set to --the results are the same.

Reproducible: Always

Steps to Reproduce:
1. Install =dev-lang/julia-1.6.0.
2. Execute Julia code such as:
  n = 3_000;
  A = rand(n,n);
  B = A[:,:];
  C=similar(A);
  @time mul!(C,A,B)
Timings differ (correctly) if OMP_NUM_THREADS are set to different values before running julia1.6 in dev-lang/julia-bin. dev-lang/julia does not appear to honour OMP_NUM_THREADS.
Actual Results:  
dev-lang/julia always takes the same amount of time to run regardless of what OMP_NUM_THREADS is set to.

Expected Results:  
When OMP_NUM_THREADS is set the time required should decrease (assuming one has enough physical cores).