Run cythonize() in parallel in "new_build_ext" if threaded distutils build was requested.

1 files changed, 3 insertions, 1 deletions

diff --git a/Cython/Distutils/build_ext.py b/Cython/Distutils/build_ext.py
index 0f3ef633f..8ca29b236 100644
--- a/Cython/Distutils/build_ext.py
+++ b/Cython/Distutils/build_ext.py
@@ -14,9 +14,11 @@ else:
 class new_build_ext(_build_ext, object):
     def finalize_options(self):
         if self.distribution.ext_modules:
+            nthreads = getattr(self, 'parallel', None)  # -j option in Py3.5+
+            nthreads = int(nthreads) if nthreads else None
             from Cython.Build.Dependencies import cythonize
             self.distribution.ext_modules[:] = cythonize(
-                self.distribution.ext_modules)
+                self.distribution.ext_modules, nthreads=nthreads)
         super(new_build_ext, self).finalize_options()
 
 # This will become new_build_ext in the future.