From 700c804368a9327f343b2616c9e475b110ebd8db Mon Sep 17 00:00:00 2001
From: Bryan <bugatti_it@163.com>
Date: Tue, 25 Jul 2023 16:49:47 +0800
Subject: [PATCH] Fix Issue #388: Celery Beat scheduled tasks may be executed
 repeatedly (#660)
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* Fix: The problem that Celery Beat scheduled tasks may be executed repeatedly

* fix: 增加 TypeError 捕获

* fix: Add tests for `test_sync_not_saves_last_run_at_while_schedule_changed`
---
 django_celery_beat/schedulers.py |  4 ++--
 t/unit/test_schedulers.py        | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/django_celery_beat/schedulers.py b/django_celery_beat/schedulers.py
index 2c1b5773..846b97a9 100644
--- a/django_celery_beat/schedulers.py
+++ b/django_celery_beat/schedulers.py
@@ -300,9 +300,9 @@ def sync(self):
             while self._dirty:
                 name = self._dirty.pop()
                 try:
-                    self.schedule[name].save()
+                    self._schedule[name].save()
                     _tried.add(name)
-                except (KeyError, ObjectDoesNotExist):
+                except (KeyError, TypeError, ObjectDoesNotExist):
                     _failed.add(name)
         except DatabaseError as exc:
             logger.exception('Database error while sync: %r', exc)
diff --git a/t/unit/test_schedulers.py b/t/unit/test_schedulers.py
index f44d88cb..dbafe666 100644
--- a/t/unit/test_schedulers.py
+++ b/t/unit/test_schedulers.py
@@ -444,6 +444,28 @@ def test_reserve(self):
         assert self.s.flushed == 1
         assert self.m2.name in self.s._dirty
 
+    def test_sync_not_saves_last_run_at_while_schedule_changed(self):
+        # Update e1 last_run_at and add to dirty
+        e1 = self.s.schedule[self.m2.name]
+        time.sleep(3)
+        e1.model.last_run_at = e1._default_now()
+        self.s._dirty.add(e1.model.name)
+
+        # Record e1 pre sync last_run_at
+        e1_pre_sync_last_run_at = e1.model.last_run_at
+
+        # Set schedule_changed() == True
+        self.s._last_timestamp = monotonic()
+        # Do sync
+        self.s.sync()
+
+        # Record e1 post sync last_run_at
+        e1_m = PeriodicTask.objects.get(pk=e1.model.pk)
+        e1_post_sync_last_run_at = e1_m.last_run_at
+
+        # Check
+        assert e1_pre_sync_last_run_at == e1_post_sync_last_run_at
+
     def test_sync_saves_last_run_at(self):
         e1 = self.s.schedule[self.m2.name]
         last_run = e1.last_run_at