Skip ready functions if not in main thread or plugins are not loaded yet (#5005)

* Skip ready functions if not in main thread or plugins are not loaded yet

* Debug integration tests

* Update ready.py

* Update ready.py

* Fix isInMainThread and isPluginRegistryLoaded ready functions

* Preload gunicorn app to only invoke the appconfig ready functions once

* debug: test prints for statistics

* Remove debug print

* Test without

* Revert "Test without"

This reverts commit 1bc1872893.

* Second test

* Add checks back to part, label, user model

* Add checks back to inventree, plugin apps

* log server output for debugging

* hopefully I can get the log this time+

* Next test

* Test with --noreload

* Next test

* trigger: ci, because session expired

* block the second ready execution instead of the first

* fix: load order

* Fix test and revert gh actions workflow change

* Added all_apps method to reload machanism

* Changed detect reload mechanism

* Also trigger ready on reload

* Add skipping second reload back for testing mode

* Added doc string back

* Update InvenTree/plugin/base/integration/AppMixin.py

InvenTree/label/apps.py

@@ -12,7 +12,8 @@ from django.conf import settings
 from django.core.exceptions import AppRegistryNotReady
 from django.db.utils import OperationalError
 
-from InvenTree.ready import canAppAccessDatabase
+from InvenTree.ready import (canAppAccessDatabase, isInMainThread,
+                             isPluginRegistryLoaded)
 
 logger = logging.getLogger("inventree")
 
@@ -35,6 +36,10 @@ class LabelConfig(AppConfig):
 
     def ready(self):
         """This function is called whenever the label app is loaded."""
+        # skip loading if plugin registry is not loaded or we run in a background thread
+        if not isPluginRegistryLoaded() or not isInMainThread():
+            return
+
         if canAppAccessDatabase(allow_test=False):
 
             try: