Merge pull request #20789 from ryan-crabbe/perf/cache-openai-init-params

perf: pre-compute OpenAI client __init__ params at module load

litellm/llms/openai/common_utils.py

@@ -14,6 +14,8 @@ from openai import AsyncAzureOpenAI, AsyncOpenAI, AzureOpenAI, OpenAI
 if TYPE_CHECKING:
     from aiohttp import ClientSession
 
+import inspect
+
 import litellm
 from litellm.llms.base_llm.chat.transformation import BaseLLMException
 from litellm.llms.custom_httpx.http_handler import (
@@ -22,6 +24,14 @@ from litellm.llms.custom_httpx.http_handler import (
     get_ssl_configuration,
 )
 
+def _get_client_init_params(cls: type) -> List[str]:
+    """Extract __init__ parameter names (excluding 'self') from a class."""
+    return [p for p in inspect.signature(cls.__init__).parameters if p != "self"]
+
+
+_OPENAI_INIT_PARAMS: List[str] = _get_client_init_params(OpenAI)
+_AZURE_OPENAI_INIT_PARAMS: List[str] = _get_client_init_params(AzureOpenAI)
+
 
 class OpenAIError(BaseLLMException):
     def __init__(
@@ -183,18 +193,10 @@ class BaseOpenAILLM:
         client_type: Literal["openai", "azure"]
     ) -> List[str]:
         """Returns a list of fields that are used to initialize the OpenAI client"""
-        import inspect
-
-        from openai import AzureOpenAI, OpenAI
-
         if client_type == "openai":
-            signature = inspect.signature(OpenAI.__init__)
+            return _OPENAI_INIT_PARAMS
         else:
-            signature = inspect.signature(AzureOpenAI.__init__)
-
-        # Extract parameter names, excluding 'self'
-        param_names = [param for param in signature.parameters if param != "self"]
-        return param_names
+            return _AZURE_OPENAI_INIT_PARAMS
 
     @staticmethod
     def _get_async_http_client(
@@ -230,3 +232,5 @@ class BaseOpenAILLM:
             verify=ssl_config,
             follow_redirects=True,
         )
+
+

tests/test_litellm/llms/openai/test_openai_common_utils.py

@@ -129,3 +129,38 @@ async def test_openai_client_reuse(function_name, is_async, args):
 
         # Verify we tried to get from cache 10 times (once per request)
         assert mock_get_cache.call_count == 10, "Should check cache for each request"
+
+
+def test_precomputed_init_params_match_inspect_signature():
+    """
+    Verify that the pre-computed _OPENAI_INIT_PARAMS and _AZURE_OPENAI_INIT_PARAMS
+    match what inspect.signature() returns. If the OpenAI SDK changes its __init__
+    params, this test will fail — signaling the constants need updating.
+    """
+    import inspect
+
+    from openai import AzureOpenAI, OpenAI
+
+    from litellm.llms.openai.common_utils import (
+        _AZURE_OPENAI_INIT_PARAMS,
+        _OPENAI_INIT_PARAMS,
+    )
+
+    expected_openai = [
+        p for p in inspect.signature(OpenAI.__init__).parameters if p != "self"
+    ]
+    expected_azure = [
+        p for p in inspect.signature(AzureOpenAI.__init__).parameters if p != "self"
+    ]
+
+    assert _OPENAI_INIT_PARAMS == expected_openai
+    assert _AZURE_OPENAI_INIT_PARAMS == expected_azure
+
+
+@pytest.mark.parametrize("client_type", ["openai", "azure"])
+def test_get_openai_client_initialization_param_fields(client_type):
+    """Verify the method returns the correct pre-computed params for each client type."""
+    result = BaseOpenAILLM.get_openai_client_initialization_param_fields(client_type)
+    assert isinstance(result, list)
+    assert len(result) > 0
+    assert "self" not in result