Issue 2644: Tasks can be run several times

- updated parameter name
- changed exit to the common approach of calling "return"

luigi/scheduler.py

@@ -150,7 +150,7 @@ class scheduler(Config):
 
     metrics_collector = parameter.EnumParameter(enum=MetricsCollectors, default=MetricsCollectors.default)
 
-    rerun_task_blocking_period = parameter.IntParameter(default=10)
+    stable_done_cooldown_secs = parameter.IntParameter(default=10)
 
     def _get_retry_policy(self):
         return RetryPolicy(self.retry_count, self.disable_hard_timeout, self.disable_window)
@@ -843,8 +843,8 @@ def add_task(self, task_id=None, status=PENDING, runnable=True,
             return
 
         # if the task was completed only recently, do not run the same task again
-        if status == PENDING and task.status == DONE and (time.time() - task.updated) < self._config.rerun_task_blocking_period:
-            status = DONE
+        if status == PENDING and task.status == DONE and (time.time() - task.updated) < self._config.stable_done_cooldown_secs:
+            return
 
         # for setting priority, we'll sometimes create tasks with unset family and params
         if not task.family:

test/scheduler_api_test.py

@@ -46,7 +46,7 @@ def get_scheduler_config(self):
             'disable_window': 10,
             'retry_count': 3,
             'disable_hard_timeout': 60 * 60,
-            'rerun_task_blocking_period': 0
+            'stable_done_cooldown_secs': 0
         }
 
     def tearDown(self):