threads: make sure logger and substitution singletons are not reused (#24078)

wcs/qommon/__init__.py

@@ -48,7 +48,7 @@ class TenantAwareThread(threading.Thread):
     def __init__(self, *args, **kwargs):
         self.publisher = copy.copy(get_publisher())
         if self.publisher:
-            self.publisher.pgconn = None
+            self.publisher.detach()
         super(TenantAwareThread, self).__init__(*args, **kwargs)
 
     def run(self):

wcs/qommon/publisher.py

@@ -767,6 +767,12 @@ class QommonPublisher(Publisher, object):
         publisher.set_config()
         return publisher
 
+    def detach(self):
+        # reset structures that would otherwise be shared between threads
+        self.pgconn = None
+        self._app_logger = None
+        self.substitutions = Substitutions()
+
     extra_dirs = None
     @classmethod
     def register_extra_dir(cls, dir):