Reduce worker idle queries

tasktiger/worker.py

@@ -160,6 +160,17 @@ def _filter_queues(self, queues):
             )
         ]
 
+    def _worker_perform_secondary_tasks(self):
+        # We should queue scheduled tasks every QUEUE_SCHEDULED_TASKS_TIME time
+        # and expired tasks every REQUEUE_EXPIRED_TASKS_INTERVAL time. Use only
+        # one Redis query to enter this block since every single worker calls
+        # this every second.
+        # XXX: Ideally, we should keep track of workers and take turns.
+        key = self._key("lock", "secondary_tasks")
+        if self.connection.set(key, "1", ex=1, nx=True):
+            self._worker_queue_scheduled_tasks()
+            self._worker_queue_expired_tasks()
+
     def _worker_queue_scheduled_tasks(self):
         """
         Helper method that takes due tasks from the SCHEDULED queue and puts
@@ -1046,8 +1057,7 @@ def _worker_run(self):
             time.time() - self._last_task_check > self.config['SELECT_TIMEOUT']
             and not self._stop_requested
         ):
-            self._worker_queue_scheduled_tasks()
-            self._worker_queue_expired_tasks()
+            self._worker_perform_secondary_tasks()
             self._last_task_check = time.time()
 
     def _queue_periodic_tasks(self):