Download requirements in parallel

pip/_vendor/concurrent/__init__.py

@@ -0,0 +1,3 @@
+from pkgutil import extend_path
+
+__path__ = extend_path(__path__, __name__)

pip/_vendor/concurrent/futures/__init__.py

@@ -0,0 +1,23 @@
+# Copyright 2009 Brian Quinlan. All Rights Reserved.
+# Licensed to PSF under a Contributor Agreement.
+
+"""Execute computations asynchronously using threads or processes."""
+
+__author__ = 'Brian Quinlan (brian@sweetapp.com)'
+
+from ._base import (FIRST_COMPLETED,
+                                      FIRST_EXCEPTION,
+                                      ALL_COMPLETED,
+                                      CancelledError,
+                                      TimeoutError,
+                                      Future,
+                                      Executor,
+                                      wait,
+                                      as_completed)
+from .thread import ThreadPoolExecutor
+
+try:
+    from .process import ProcessPoolExecutor
+except ImportError:
+    # some platforms don't have multiprocessing
+    pass