Add entry for Barrier objects.
diff --git a/Doc/whatsnew/3.2.rst b/Doc/whatsnew/3.2.rst
index 84e5ee6..e49db1e 100644
--- a/Doc/whatsnew/3.2.rst
+++ b/Doc/whatsnew/3.2.rst
@@ -817,7 +817,49 @@
(Contributed by Raymond Hettinger.)
-.. XXX threading.py and Barrier objects
+threading
+---------
+
+The :mod:`threading` module has a new :class:`~threading.Barrier`
+synchronization class for making multiple threads wait until all of them have
+reached a common barrier point. Barriers are useful for making sure that a task
+with multiple preconditions does not run until all of the predecessor tasks are
+complete.
+
+Barriers can work with an arbitrary number of threads. This is a generalization
+of a `Rendezvous <http://en.wikipedia.org/wiki/Synchronous_rendezvous>`_ which
+is defined for only two threads.
+
+The barrier is designed to be cyclic, making it reusable once all of the
+waiting threads are released.
+
+If any of the predecessor tasks can hang or be delayed, a barrier can be created
+with an optional *timeout* parameter. Then if the timeout period elapses before
+all the predecessor tasks reach the barrier point, all waiting threads are
+released and a :exc:`~threading.BrokenBarrierError` exception is raised.
+
+Example of using barriers::
+
+ def get_votes(site):
+ ballots = conduct_election(site)
+ all_polls_closed.wait() # do not count until all polls are closed
+ summarize(ballots)
+
+ all_polls_closed = Barrier(len(sites))
+ for site in sites(get_votes(site)):
+ Thread(target=get_votes, args=(site,)).start()
+
+In this example, the barrier enforces a rule that votes cannot be counted at any
+polling site until all polls are closed. Notice how a solution with a barrier
+is similar to one with :meth:`threading.Thread.join`, but the threads stay alive
+and continue to do work (summarizing ballots) after the barrier point is
+crossed.
+
+See `Barrier Synchronization Patterns
+<http://parlab.eecs.berkeley.edu/wiki/_media/patterns/paraplop_g1_3.pdf>`_
+for more examples of how barriers can be used in parallel computing.
+
+(Contributed by Kristján Valur Jónsson in :issue:`8777`.)
datetime
--------