speed up domain loading

Domain loading is extremely slow for large bots - about 5 Mins for a 3.3 MBytes domain (including responses), and that is due to multiple times loading and parsing the same file.
This commit addresses that, be removing the validation if loading from a model tar.gz and loading the file(s) only once if reading from a directory.

rasa/graph_components/providers/domain_provider.py

@@ -45,7 +45,7 @@ def load(
     ) -> DomainProvider:
         """Creates provider using a persisted version of itself."""
         with model_storage.read_from(resource) as resource_directory:
-            domain = Domain.from_path(resource_directory)
+            domain = Domain.from_path(resource_directory, is_validated=True)
         return cls(model_storage, resource, domain)
 
     def _persist(self, domain: Domain) -> None:

rasa/shared/core/domain.py

@@ -188,20 +188,21 @@ def load(cls, paths: Union[List[Union[Path, Text]], Text, Path]) -> "Domain":
         return domain
 
     @classmethod
-    def from_path(cls, path: Union[Text, Path]) -> "Domain":
+    def from_path(cls, path: Union[Text, Path], is_validated: bool = False) -> "Domain":
         """Loads the `Domain` from a path."""
+        logger.debug(f"Loading from {path}")
         path = os.path.abspath(path)
 
         if os.path.isfile(path):
             domain = cls.from_file(path)
         elif os.path.isdir(path):
-            domain = cls.from_directory(path)
+            domain = cls.from_directory(path, is_validated=is_validated)
         else:
             raise InvalidDomain(
                 "Failed to load domain specification from '{}'. "
                 "File not found!".format(os.path.abspath(path))
             )
-
+        logger.debug(f"done loading domain from {path}")
         return domain
 
     @classmethod
@@ -287,20 +288,30 @@ def _get_session_config(session_config: Dict) -> SessionConfig:
         return SessionConfig(session_expiration_time_min, carry_over_slots)
 
     @classmethod
-    def from_directory(cls, path: Text) -> "Domain":
+    def from_directory(cls, path: Text, is_validated: bool = False) -> "Domain":
         """Loads and merges multiple domain files recursively from a directory tree."""
         combined: Dict[Text, Any] = {}
         for root, _, files in os.walk(path, followlinks=True):
             for file in files:
+                logger.debug(f"Processing {file=}")
                 full_path = os.path.join(root, file)
-                if Domain.is_domain_file(full_path):
-                    _ = Domain.from_file(full_path)  # does the validation here only
-                    other_dict = rasa.shared.utils.io.read_yaml(
-                        rasa.shared.utils.io.read_file(full_path)
-                    )
+                logger.debug(f"Checking file type of {file=}")
+                if other_dict := Domain.is_domain_file(full_path):
+                    if not is_validated:
+                        logger.debug(f"Validating {file=}")
+                        _ = Domain.from_dict(
+                            other_dict
+                        )  # does the validation here only
+                        # logger.debug(f"Reading {file=}")
+                        # other_dict = rasa.shared.utils.io.read_yaml(
+                        #     rasa.shared.utils.io.read_file(full_path)
+                        # )
+                    logger.debug(f"Merging {file=}")
                     combined = Domain.merge_domain_dicts(other_dict, combined)
 
+        logger.debug("Building domain from dict.")
         domain = Domain.from_dict(combined)
+        logger.debug(f"Merged domain from directory {path=}")
         return domain
 
     def merge(
@@ -1802,7 +1813,7 @@ def is_domain_file(filename: Union[Text, Path]) -> bool:
             filename: Path of the file which should be checked.
 
         Returns:
-            `True` if it's a domain file, otherwise `False`.
+            a domain file, otherwise `False`.
 
         Raises:
             YamlException: if the file seems to be a YAML file (extension) but
@@ -1824,7 +1835,10 @@ def is_domain_file(filename: Union[Text, Path]) -> bool:
             )
             return False
 
-        return any(key in content for key in ALL_DOMAIN_KEYS)
+        if any(key in content for key in ALL_DOMAIN_KEYS):
+            return content
+        else:
+            return False
 
     def required_slots_for_form(self, form_name: Text) -> List[Text]:
         """Retrieve the list of required slot names for a form defined in the domain.