Don't use 100% CPU when bucket queue is empty, also print the scheduler debug logs less frequently.

celery/worker/controllers.py

@@ -86,11 +86,10 @@ class Mediator(BackgroundThread):
         """Get tasks from bucket queue and apply the task callback."""
         logger = get_default_logger()
         try:
-            logger.debug("Mediator: Trying to get message from ready_queue")
             # This blocks until there's a message in the queue.
             task = self.ready_queue.get(timeout=1)
         except QueueEmpty:
-            logger.debug("Mediator: Bucket queue is empty.")
+            time.sleep(1)
         else:
             logger.debug("Mediator: Running callback for task: %s[%s]" % (
                 task.task_name, task.task_id))
@@ -103,13 +102,23 @@ class ScheduleController(BackgroundThread):
     def __init__(self, eta_schedule):
         super(ScheduleController, self).__init__()
         self._scheduler = iter(eta_schedule)
+        self.iterations = 0
 
     def on_iteration(self):
         """Wake-up scheduler"""
         logger = get_default_logger()
-        logger.debug("ScheduleController: Scheduler wake-up")
         delay = self._scheduler.next()
-        logger.debug(
-            "ScheduleController: Next wake-up estimated at %s seconds..." % (
-                delay))
+        debug_log = True
+        if delay is None:
+            delay = 1
+            if self.iterations == 10:
+                self.iterations = 0
+            else:
+                debug_log = False
+                self.iterations += 1
+        if debug_log:
+            logger.debug("ScheduleController: Scheduler wake-up")
+            logger.debug(
+                "ScheduleController: Next wake-up eta %s seconds..." % (
+                    delay))
         time.sleep(delay)