1 files changed, 57 insertions, 0 deletions
diff --git a/Lib/lib2to3/refactor.py b/Lib/lib2to3/refactor.py
index c0ba196..b679db4 100755
--- a/Lib/lib2to3/refactor.py
+++ b/Lib/lib2to3/refactor.py
@@ -506,6 +506,63 @@ class RefactoringTool(object):
             yield ""
 
 
+class MultiprocessingUnsupported(Exception):
+    pass
+
+
+class MultiprocessRefactoringTool(RefactoringTool):
+
+    def __init__(self, *args, **kwargs):
+        super(MultiprocessRefactoringTool, self).__init__(*args, **kwargs)
+        self.queue = None
+
+    def refactor(self, items, write=False, doctests_only=False,
+                 num_processes=1):
+        if num_processes == 1:
+            return super(MultiprocessRefactoringTool, self).refactor(
+                items, write, doctests_only)
+        try:
+            import multiprocessing
+        except ImportError:
+            raise MultiprocessingUnsupported
+        if self.queue is not None:
+            raise RuntimeError("already doing multiple processes")
+        self.queue = multiprocessing.JoinableQueue()
+        processes = [multiprocessing.Process(target=self._child)
+                     for i in xrange(num_processes)]
+        try:
+            for p in processes:
+                p.start()
+            super(MultiprocessRefactoringTool, self).refactor(items, write,
+                                                              doctests_only)
+        finally:
+            self.queue.join()
+            for i in xrange(num_processes):
+                self.queue.put(None)
+            for p in processes:
+                if p.is_alive():
+                    p.join()
+            self.queue = None
+
+    def _child(self):
+        task = self.queue.get()
+        while task is not None:
+            args, kwargs = task
+            try:
+                super(MultiprocessRefactoringTool, self).refactor_file(
+                    *args, **kwargs)
+            finally:
+                self.queue.task_done()
+            task = self.queue.get()
+
+    def refactor_file(self, *args, **kwargs):
+        if self.queue is not None:
+            self.queue.put((args, kwargs))
+        else:
+            return super(MultiprocessRefactoringTool, self).refactor_file(
+                *args, **kwargs)
+
+
 def diff_texts(a, b, filename):
     """Return a unified diff of two strings."""
     a = a.splitlines()