Merge pull request #347 from maerteijn/fix-scheduler-concurrency

Fix scheduler concurrency with multiple clusters

django_q/cluster.py

@@ -203,7 +203,6 @@ class Sentinel(object):
         self.start_event.set()
         Stat(self).save()
         logger.info(_('Q Cluster-{} running.').format(self.parent_pid))
-        scheduler(broker=self.broker)
         counter = 0
         cycle = Conf.GUARD_CYCLE  # guard loop sleep in seconds
         # Guard loop. Runs at least once
@@ -492,7 +491,8 @@ def scheduler(broker=None):
         broker = get_broker()
     db.close_old_connections()
     try:
-        for s in Schedule.objects.exclude(repeats=0).filter(next_run__lt=timezone.now()):
+        with db.transaction.atomic():
+            for s in Schedule.objects.select_for_update().exclude(repeats=0).filter(next_run__lt=timezone.now()):
                 args = ()
                 kwargs = {}
                 # get args, kwargs and hook
@@ -530,9 +530,7 @@ def scheduler(broker=None):
                             next_run = next_run.shift(years=+1)
                         if Conf.CATCH_UP or next_run > arrow.utcnow():
                             break
-                # arrow always returns a tz aware datetime, and we don't want
-                # this when we explicitly configured django with USE_TZ=False
-                s.next_run = next_run.datetime if settings.USE_TZ else next_run.datetime.replace(tzinfo=None)
+                    s.next_run = next_run.datetime
                     s.repeats += -1
                 # send it to the cluster
                 q_options['broker'] = broker

docs/conf.py

@@ -44,8 +44,8 @@ extensions = [
 ]
 
 intersphinx_mapping = {'python': ('https://docs.python.org/3.5', None),
-                       'django': ('https://docs.djangoproject.com/en/1.8/',
-                                  'https://docs.djangoproject.com/en/1.8//_objects/')}
+                       'django': ('https://docs.djangoproject.com/en/2.2/',
+                                  'https://docs.djangoproject.com/en/2.2/_objects/')}
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']