Update uvicorn server configuration and add pool config (#2052)

The Makefile has been updated to add support for specifying the number
of workers for the uvicorn server. The pyproject.toml file has also been
updated to upgrade the uvicorn dependency to version 0.30.0.
Additionally, the DatabaseService class in service.py has been
refactored to use the pool_size and max_overflow settings from the
SettingsService. This change allows for better control over the number
of connections in the connection pool and the number of connections that
can be opened beyond the pool size. The create_engine function has also
been modified to pass the pool_size and max_overflow parameters.

Makefile

@@ -7,6 +7,7 @@ port ?= 7860
 env ?= .env
 open_browser ?= true
 path = src/backend/base/langflow/frontend
+workers ?= 1
 
 codespell:
 	@poetry install --with spelling
@@ -144,10 +145,10 @@ backend:
 	@-kill -9 $(lsof -t -i:7860)
 ifdef login
 	@echo "Running backend autologin is $(login)";
-	LANGFLOW_AUTO_LOGIN=$(login) poetry run uvicorn --factory langflow.main:create_app --host 0.0.0.0 --port 7860 --reload --env-file .env --loop asyncio
+	LANGFLOW_AUTO_LOGIN=$(login) poetry run uvicorn --factory langflow.main:create_app --host 0.0.0.0 --port 7860 --reload --env-file .env --loop asyncio --workers $(workers)
 else
 	@echo "Running backend respecting the .env file";
-	poetry run uvicorn --factory langflow.main:create_app --host 0.0.0.0 --port 7860 --reload --env-file .env  --loop asyncio
+	poetry run uvicorn --factory langflow.main:create_app --host 0.0.0.0 --port 7860 --reload --env-file .env  --loop asyncio --workers $(workers)
 endif
 
 build_and_run:

src/backend/base/langflow/components/models/OpenAIModel.py

@@ -78,7 +78,7 @@ def build(
         self,
         input_value: Text,
         openai_api_key: str,
-        temperature: Optional[float] = 0.1,
+        temperature: float = 0.1,
         model_name: str = "gpt-4o",
         max_tokens: Optional[int] = 256,
         model_kwargs: NestedDict = {},

src/backend/base/langflow/services/database/factory.py

@@ -15,4 +15,4 @@ def create(self, settings_service: "SettingsService"):
         # Here you would have logic to create and configure a DatabaseService
         if not settings_service.settings.database_url:
             raise ValueError("No database URL provided")
-        return DatabaseService(settings_service.settings.database_url)
+        return DatabaseService(settings_service)

src/backend/base/langflow/services/database/service.py

@@ -21,12 +21,17 @@
 if TYPE_CHECKING:
     from sqlalchemy.engine import Engine
 
+    from langflow.services.settings.service import SettingsService
+
 
 class DatabaseService(Service):
     name = "database_service"
 
-    def __init__(self, database_url: str):
-        self.database_url = database_url
+    def __init__(self, settings_service: "SettingsService"):
+        self.settings_service = settings_service
+        if settings_service.settings.database_url is None:
+            raise ValueError("No database URL provided")
+        self.database_url: str = settings_service.settings.database_url
         # This file is in langflow.services.database.manager.py
         # the ini is in langflow
         langflow_dir = Path(__file__).parent.parent.parent
@@ -41,7 +46,12 @@ def _create_engine(self) -> "Engine":
             connect_args = {"check_same_thread": False}
         else:
             connect_args = {}
-        return create_engine(self.database_url, connect_args=connect_args)
+        return create_engine(
+            self.database_url,
+            connect_args=connect_args,
+            pool_size=self.settings_service.settings.pool_size,
+            max_overflow=self.settings_service.settings.max_overflow,
+        )
 
     def __enter__(self):
         self._session = Session(self.engine)
@@ -267,3 +277,4 @@ def teardown(self):
             logger.error(f"Error tearing down database: {exc}")
 
         self.engine.dispose()
+        self.engine.dispose()

src/backend/base/langflow/services/settings/base.py

@@ -67,6 +67,11 @@ class Settings(BaseSettings):
 
     dev: bool = False
     database_url: Optional[str] = None
+    """Database URL for Langflow. If not provided, Langflow will use a SQLite database."""
+    pool_size: int = 10
+    """The number of connections to keep open in the connection pool. If not provided, the default is 10."""
+    max_overflow: int = 10
+    """The number of connections to allow that can be opened beyond the pool size. If not provided, the default is 10."""
     cache_type: str = "async"
     remove_api_keys: bool = False
     components_path: List[str] = []

src/backend/base/pyproject.toml

@@ -28,7 +28,7 @@ langflow-base = "langflow.__main__:main"
 python = ">=3.10,<3.13"
 fastapi = "^0.111.0"
 httpx = "*"
-uvicorn = "^0.29.0"
+uvicorn = "^0.30.0"
 gunicorn = "^22.0.0"
 langchain = "~0.2.0"
 langchainhub = "~0.1.15"