diff --git a/README.md b/README.md index 648143ad..108b223f 100644 --- a/README.md +++ b/README.md @@ -322,10 +322,12 @@ https://github.com/xianyi/OpenBLAS/issues/2985). and workarounds: https://github.com/joblib/threadpoolctl/blob/master/multiple_openmp.md -- Setting the maximum number of threads of the OpenMP and BLAS libraries has a global - effect and impacts the whole Python process. There is no thread level isolation as - these libraries do not offer thread-local APIs to configure the number of threads to - use in nested parallel calls. +- Setting the maximum number of threads of BLAS libraries such as OpenBLAS with + the pthreads threading layer and MKL has a global effect and impacts the whole + Python process. By contrast, for OpenMP runtimes such as libgomp and libomp, + `omp_set_num_threads` applies to the calling thread. Therefore, when + `threadpool_limits` limits OpenMP libraries, the limit is applied on the + current thread and does not propagate to threads spawned afterward. ## Maintainers