Fixed Executor.map() being greedy

CHANGES

@@ -1,3 +1,9 @@
+3.0.1
+=====
+
+- Made Executor.map() non-greedy
+
+
 3.0.0
 =====
 

concurrent/futures/_base.py

@@ -4,6 +4,7 @@
 import collections
 import logging
 import threading
+import itertools
 import time
 
 __author__ = 'Brian Quinlan (brian@sweetapp.com)'
@@ -567,7 +568,7 @@ class Executor(object):
         if timeout is not None:
             end_time = timeout + time.time()
 
-        fs = [self.submit(fn, *args) for args in zip(*iterables)]
+        fs = [self.submit(fn, *args) for args in itertools.izip(*iterables)]
 
         # Yield must be hidden in closure so that the futures are submitted
         # before the first iterator value is required.