Tornado update

libs/tornado/httpclient.py

@@ -33,7 +33,7 @@ import functools
 import time
 import weakref
 
-from tornado.concurrent import Future
+from tornado.concurrent import TracebackFuture
 from tornado.escape import utf8
 from tornado import httputil, stack_context
 from tornado.ioloop import IOLoop
@@ -144,9 +144,16 @@ class AsyncHTTPClient(Configurable):
 
     def close(self):
         """Destroys this HTTP client, freeing any file descriptors used.
-        Not needed in normal use, but may be helpful in unittests that
-        create and destroy http clients.  No other methods may be called
-        on the `AsyncHTTPClient` after ``close()``.
+
+        This method is **not needed in normal use** due to the way
+        that `AsyncHTTPClient` objects are transparently reused.
+        ``close()`` is generally only necessary when either the
+        `.IOLoop` is also being closed, or the ``force_instance=True``
+        argument was used when creating the `AsyncHTTPClient`.
+
+        No other methods may be called on the `AsyncHTTPClient` after
+        ``close()``.
+
         """
         if self._async_clients().get(self.io_loop) is self:
             del self._async_clients()[self.io_loop]
@@ -174,7 +181,7 @@ class AsyncHTTPClient(Configurable):
         # where normal dicts get converted to HTTPHeaders objects.
         request.headers = httputil.HTTPHeaders(request.headers)
         request = _RequestProxy(request, self.defaults)
-        future = Future()
+        future = TracebackFuture()
         if callback is not None:
             callback = stack_context.wrap(callback)