Description Florian Best 2024-03-01 17:55:55 CET

There are memory leaks in the UMC-server:

1. univention.management.console.resource.Resource.get_current_user() assigns a fake translation function for the session, which holds a reference the the Resource/RequestHandler. The RequestHandler is therefore never garbage collected.

     def get_current_user(self):
         session = Session.get_or_create(self.get_session_id())  # FIXME: this creates a Session instance even if the session does not exists
-        session._ = lambda *args: self._(*args)  # hack to prevent circular use, when "_" is not yet set but only in prepare()  # noqa: PLW0108
+        weakself = weakref.ref(self)
+        session._ = lambda *args: weakself()._(*args)  # hack to prevent circular use, when "_" is not yet set but only in prepare()  # noqa: PLW0108
         if not session.user.ip:
             session.user.ip = self.get_ip_address()
         return session


2. univention.management.console.message.Request.get_user_ldap_connection() adds a "self.bind_user_connection" reference to a LDAP connection cache (in .ldap.LDAP.__ldap_connections), which references the Request object, so that this is never garbage collected.

     def get_user_ldap_connection(self, no_cache=False, **kwargs):
         if not self.user_dn:
             return  # local user (probably root)
+
+        wheakself = weakref.ref(self)
+
+        def bind_user_connection(lo):
+            return wheakself().bind_user_connection(lo)
+
         try:
-            lo, _po = get_user_connection(bind=self.bind_user_connection, write=kwargs.pop('write', False), follow_referral=True, no_cache=no_cache, **kwargs)
+            lo, _po = get_user_connection(bind=bind_user_connection, write=kwargs.pop('write', False), follow_referral=True, no_cache=no_cache, **kwargs)


3. univention.management.console.session.Session passes "self" to .IACLs and .Processes, which holds them so that a circular reference exists.
Note that Session.renew() throws away the IACLs and Processes instances, without e.g. unassigning the .session reference, which will cause that they never get garbage collected.