changeset:   88339:9223dfa2ae5b
tag:         tip
parent:      88336:247f12fecf2b
user:        Torsten Landschoff <torsten@landschoff.net>
date:        Mon Jan 06 16:28:03 2014 +0100
summary:     multiprocessing.Queue(timeout=x) always polls the Queue if x >= 0.

diff -r 247f12fecf2b -r 9223dfa2ae5b Lib/multiprocessing/queues.py
--- a/Lib/multiprocessing/queues.py	Sun Jan 05 12:00:31 2014 -0800
+++ b/Lib/multiprocessing/queues.py	Mon Jan 06 16:28:03 2014 +0100
@@ -102,8 +102,14 @@
                 raise Empty
             try:
                 if block:
+                    # Make sure that we poll for data at least once whatever
+                    # the timeout.
                     timeout = deadline - time.time()
-                    if timeout < 0 or not self._poll(timeout):
+                    if timeout < 0:
+                        empty = not self._poll()
+                    else:
+                        empty = not self._poll(timeout)
+                    if empty:
                         raise Empty
                 elif not self._poll():
                     raise Empty
diff -r 247f12fecf2b -r 9223dfa2ae5b Lib/test/_test_multiprocessing.py
--- a/Lib/test/_test_multiprocessing.py	Sun Jan 05 12:00:31 2014 -0800
+++ b/Lib/test/_test_multiprocessing.py	Mon Jan 06 16:28:03 2014 +0100
@@ -725,6 +725,19 @@
         delta = time.time() - start
         self.assertGreaterEqual(delta, 0.18)
 
+    def test_timeout_0(self):
+        # timeout=0 should be equivalent to block=False. As should a very small timeout.
+        q = multiprocessing.Queue()
+        q.put("hi")
+        q.put("there")
+        # We need to sleep here to give the queue feeder thread time to feed the queue.
+        # Unfortunately, there is nothing like "flush" to make sure that the data we
+        # just put actually arrived in the queue.
+        time.sleep(0.1)
+        # Once the data is on the receiver side, q.get should retrieve it whatever the
+        # timeout.
+        assert q.get(timeout=0) == "hi"
+        assert q.get(timeout=1e-6) == "there"
 #
 #
 #