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Prevent after-fork number of OMP threads being bigger than 1. #16999
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This could happen if it was set in the environment. As we are setting engine::OpenMP::Get()->set_enabled(false) in initialize.cc in the child after forking, the behaviour goes back to what it was before apache#15762 was introduced. Regions using omp get the threads count from GetRecommendedOMPThreadCount, so if omp is disabled they will get 1 thread and run serially
anirudh2290
reviewed
Dec 7, 2019
anirudh2290
reviewed
Dec 7, 2019
apeforest
reviewed
Dec 7, 2019
apeforest
reviewed
Dec 7, 2019
apeforest
reviewed
Dec 7, 2019
szha
reviewed
Dec 8, 2019
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@szha no. What behaviour do you suggest would be reasonable under a notebook? Leave omp threads set to 1 or to the generous value. Is there a way to detect the runtime is Jupyter? |
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@szha do you have any reference on this? If you start python in your shell, the process is also forked. But as |
anirudh2290
approved these changes
Dec 11, 2019
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Description
This could happen if it was set in the environment. As we are setting engine::OpenMP::Get()->set_enabled(false) in initialize.cc in the child after forking, the behaviour goes back to what it was before #15762 was introduced.
Regions using omp get the threads count from GetRecommendedOMPThreadCount, so if omp is disabled they will get 1 thread and run serially
@anirudh2290 @apeforest