Index: Queue.py
===================================================================
--- Queue.py	(revision 43025)
+++ Queue.py	(working copy)
@@ -35,7 +35,41 @@
         # Notify not_full whenever an item is removed from the queue;
         # a thread waiting to put is notified then.
         self.not_full = threading.Condition(self.mutex)
+        # Notify waiter whenever the number of unfinished tasks drops to zero;
+        # thread waiting to join() is notified to resume
+        self.waiter = threading.Condition(self.mutex)
+        self.unfinished_tasks = 0
 
+    def task_done(self):
+        """Indicate that a formerly enqueued task is complete.
+
+        Used by Queue consumer threads.  For each get() used to fetch a task,
+        there should be a subsequent call to task_done() when processing on
+        that task is complete.
+
+        When all pending tasks have been completed, notify a thread waiting to
+        join() to resume when all items have been processed.
+        """
+        self.waiter.acquire()
+        self.unfinished_tasks -= 1
+        if not self.unfinished_tasks:
+            self.waiter.notify()
+        self.waiter.release()
+
+    def join(self):
+        """Blocks until items in the Queue have been gotten and processed.
+
+        The count of unfinished tasks goes up whenever an item is added to the
+        Queue. The count goes down whenever a consumer thread makes a task_done()
+        call (indicating the item was retrieved and all work on it is complete).
+
+        When the count of unfinished tasks drops to zero, join() unblocks.
+        """
+        self.waiter.acquire()
+        while self.unfinished_tasks:
+                self.waiter.wait()
+        self.waiter.release()
+
     def qsize(self):
         """Return the approximate size of the queue (not reliable!)."""
         self.mutex.acquire()
@@ -86,6 +120,7 @@
                         raise Full
                     self.not_full.wait(remaining)
             self._put(item)
+            self.unfinished_tasks += 1
             self.not_empty.notify()
         finally:
             self.not_full.release()