Log warnings when internal queue is full

motorway/messages.py

@@ -3,6 +3,8 @@
 import traceback
 import uuid
 import datetime
+
+import zmq.backend.cython.constants
 from isodate import duration_isoformat
 from motorway.utils import DateTimeAwareJsonEncoder
 import logging
@@ -81,8 +83,10 @@ def send(self, queue, producer_uuid=None):
             self.producer_uuid = producer_uuid
         elif not self.producer_uuid:
             assert self.producer_uuid
-        queue.send(
-            self.as_json()
+
+        queue.send_string(
+            self.as_json(),
+            flags=zmq.backend.cython.constants.NOBLOCK # Raise an exception if the queue is full.
         )
 
     def send_control_message(self, controller_queue, time_consumed=None, process_name=None, destination_endpoint=None,
@@ -113,7 +117,7 @@ def send_control_message(self, controller_queue, time_consumed=None, process_nam
             'producer_uuid': self.producer_uuid,
             'destination_endpoint': destination_endpoint,
             'destination_uuid': destination_uuid
-        })
+        }, flags=zmq.backend.cython.constants.NOBLOCK)
 
     def ack(self, time_consumed=None):
         """

motorway/mixins.py

@@ -1,6 +1,7 @@
 import datetime
 
 import itertools
+import logging
 import random
 import socket
 import uuid
@@ -14,6 +15,9 @@
 from motorway.utils import set_timeouts_on_socket, get_connections_block, get_ip
 
 
+logger = logging.getLogger(__name__)
+
+
 class GrouperMixin(object):
     def get_grouper(self, grouper_name):
         if grouper_name == "HashRingGrouper":
@@ -42,14 +46,23 @@ def send_message(self, message, process_id, time_consumed=None, sender=None, con
         try:
             socket_addresses = self.grouper_instance.get_destinations_for(message.grouping_value)
         except GroupingValueMissing:
-            raise GroupingValueMissing("Message '%s' provided an invalid grouping_value: '%s'" % (message.content, message.grouping_value))
+            raise GroupingValueMissing("Message '%s' provided an invalid grouping_value: '%s'" %
+                                       (message.content, message.grouping_value))
         for destination in socket_addresses:
-            message.send(
-                self.send_socks[destination],
-                process_id
-            )
+            # Keep trying to send the message until successful
+            message_retries = 0
+            while True:
+                try:
+                    message.send(self.send_socks[destination], process_id)
+                    break
+                # Queue was full or not available
+                except zmq.Again as e:
+                    message_retries +=1
+                    logger.warning("Failed to send message from %s (retry # %s)", process_id, message_retries)
+                    time.sleep(5)
+
             if self.controller_sock and self.send_control_messages and control_message:
-                for index in xrange(0, retries):
+                for index in range(0, retries):
                     try:
                         message.send_control_message(
                             self.controller_sock,
@@ -59,8 +72,9 @@ def send_message(self, message, process_id, time_consumed=None, sender=None, con
                             destination_endpoint=destination,
                             sender=sender
                         )
-                        break
+                        break  # Exit retry
                     except KeyError:  # If destination is not known, lookup fails
+                        logger.warning("Destination unknown for message %s, sender %s", message, sender)
                         time.sleep(random.randrange(1, 3))  # random to avoid peak loads when running multiple processes
                     except zmq.Again:  # If connection fails, retry
                         time.sleep(random.randrange(1, 3))

motorway/tests/utils.py

@@ -5,7 +5,7 @@ class ZMQSockMock(object):
     def __init__(self, control_messages):
         self.control_messages = control_messages
 
-    def send_json(self, message):
+    def send_json(self, message, flags=None):
         self.control_messages.append(message)