gcc, OpenMP and Anaconda MKL issue

[siudej]

It seems impossible to run OpenMP 4.0 code generated by gcc inside Anaconda with MKL in Linux. The issue is that MKL is linked against libiomp5, while gcc is using incompatible libgomp. This breaks task depend clauses.

When libgomp is imported before numpy , then depend clauses work, but MKL is no longer multithreaded.

Strangely, there is no conflict on Mac. Maybe Anaconda libiomp5 on Mac does not implement libgomp symbols at all, so the libraries can coexist?

Two possible fixes:

• Forget depend and revert to taskwait. Then Floyd-Warshall will be slightly slower.
• Switch to clang-3.8, which generates libiomp5 compatible code. Hopefully this does not break anything else.

In either case, we should use ctypes to import a shared library.