fix: Resolve SQLAlchemy async engine pool configuration for SQLite

Explicitly set AsyncAdaptedQueuePool for SQLite connections to address potential async engine configuration issues. This ensures proper pool handling when creating database connections, particularly for SQLite databases.

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

@@ -14,7 +14,7 @@
 from alembic import command, util
 from alembic.config import Config
 from loguru import logger
-from sqlalchemy import event, exc, inspect
+from sqlalchemy import AsyncAdaptedQueuePool, event, exc, inspect
 from sqlalchemy.dialects import sqlite as dialect_sqlite
 from sqlalchemy.engine import Engine
 from sqlalchemy.exc import OperationalError
@@ -39,6 +39,7 @@ class DatabaseService(Service):
     name = "database_service"
 
     def __init__(self, settings_service: SettingsService):
+        self._logged_pragma = False
         self.settings_service = settings_service
         if settings_service.settings.database_url is None:
             msg = "No database URL provided"
@@ -67,8 +68,6 @@ def __init__(self, settings_service: SettingsService):
         else:
             self.alembic_log_path = Path(langflow_dir) / alembic_log_file
 
-        self._logged_pragma = False
-
     async def initialize_alembic_log_file(self):
         # Ensure the directory and file for the alembic log file exists
         await anyio.Path(self.alembic_log_path.parent).mkdir(parents=True, exist_ok=True)
@@ -119,13 +118,19 @@ def _create_engine(self) -> AsyncEngine:
 
         if url_components[0].startswith("sqlite"):
             scheme = "sqlite+aiosqlite"
+            # Even though the docs say this is the default, it raises an error
+            # if we don't specify it.
+            # https://docs.sqlalchemy.org/en/20/errors.html#pool-class-cannot-be-used-with-asyncio-engine-or-vice-versa
+            pool = AsyncAdaptedQueuePool
         else:
             scheme = "postgresql+psycopg" if url_components[0].startswith("postgresql") else url_components[0]
+            pool = None
 
         database_url = f"{scheme}://{url_components[1]}"
         return create_async_engine(
             database_url,
             connect_args=self._get_connect_args(),
+            poolclass=pool,
             **kwargs,
         )