How Parallelism is done in scikit-learn

[vineel96]

Hello,

above diagram is taken from https://pypackaging-native.github.io/key-issues/native-dependencies/blas_openmp/

1. In the above block diagram, how scikit-learn is directly dependent or directly build on openMP?
2. Is there any threading done in scikit-learn apart from openMP?
3. Why high level multi-threading is not done in scikit-learn (ex in machine learning algorithms)? why we need to use joblib again externally?

[adrinjalali]

There are different levels of parallelism, all explained here: https://scikit-learn.org/stable/computing/parallelism.html