Merge pull request #3272 from hsoft/parallel-builds

Fix builds with --parallel

mp_compile.py

@@ -1,5 +1,7 @@
 # A monkey patch of the base distutils.ccompiler to use parallel builds
 # Tested on 2.7, looks to be identical to 3.3.
+# Only applied on Python < 3.5 because otherwise, it conflicts with Python's
+# own newly-added support for parallel builds.
 
 from __future__ import print_function
 from multiprocessing import Pool, cpu_count
@@ -77,4 +79,6 @@ def install():
               "%s processes" % MAX_PROCS)
 
 
-install()
+# We monkeypatch only versions earlier than 3.5
+if sys.version_info < (3, 5):
+    install()

setup.py

@@ -205,6 +205,12 @@ class pil_build_ext(build_ext):
         if self.debug:
             global DEBUG
             DEBUG = True
+        if sys.version_info >= (3, 5) and not self.parallel:
+            # For Python < 3.5, we monkeypatch distutils to have parallel
+            # builds. If --parallel (or -j) wasn't specified, we want to
+            # reproduce the same behavior as before, that is, auto-detect the
+            # number of jobs.
+            self.parallel = mp_compile.MAX_PROCS
         for x in self.feature:
             if getattr(self, 'disable_%s' % x):
                 setattr(self.feature, x, False)