don't kill if pid same as file (#8997) (#8998)

* don't kill if pid same as file (#8997)

* test for don't kill if pid same as file (#8997)

* restore file permission

---------

Co-authored-by: Asif Saif Uddin <auvipy@gmail.com>

celery/platforms.py

@@ -186,6 +186,9 @@ def remove_if_stale(self):
         if not pid:
             self.remove()
             return True
+        if pid == os.getpid():
+            # this can be common in k8s pod with PID of 1 - don't kill
+            return True
 
         try:
             os.kill(pid, 0)

t/unit/utils/test_platforms.py

@@ -689,6 +689,15 @@ def test_remove_if_stale_no_pidfile(self):
         assert p.remove_if_stale()
         p.remove.assert_called_with()
 
+    def test_remove_if_stale_same_pid(self):
+        p = Pidfile('/var/pid')
+        p.read_pid = Mock()
+        p.read_pid.return_value = os.getpid()
+        p.remove = Mock()
+
+        assert p.remove_if_stale()
+        p.remove.assert_not_called()
+
     @patch('os.fsync')
     @patch('os.getpid')
     @patch('os.open')