check fds are closed for queue pipes

diff --git a/vimap/queue_manager.py b/vimap/queue_manager.py
index b646b92..9572400 100644
--- a/vimap/queue_manager.py
+++ b/vimap/queue_manager.py
@@ -77,6 +77,12 @@ class VimapQueueManager(object):
                 print("Main thread queue manager: Closing and joining {0} queue".format(name))
             queue.close()
             queue.join_thread()
+            while not queue._reader.closed:
+                print("Reader for queue {0} not closed, sleeping".format(name))
+                time.sleep(0.1)
+            while not queue._writer.closed:
+                print("Writer for queue {0} not closed, sleeping".format(name))
+                time.sleep(0.1)

         _close_queue('input', self.input_queue)
         del self.input_queue  # Make future accesses fail