fix: register async client cleanup eagerly to prevent SSL exit errors.

Closes #23278

litellm/__init__.py

@@ -1650,6 +1650,15 @@ if TYPE_CHECKING:
 # Track if async client cleanup has been registered (for lazy loading)
 _async_client_cleanup_registered = False
 
+# Register async client cleanup eagerly so it runs even when only eagerly-imported
+# symbols (e.g. `acompletion`, imported via `from .main import *`) are used.
+# Without this, __getattr__ is never triggered and SSL connections are left open
+# at process exit, causing "Fatal error on SSL transport" / "Event loop is closed"
+# tracebacks with asyncio.gather (see issue #23278).
+from litellm.llms.custom_httpx.async_client_cleanup import register_async_client_cleanup
+register_async_client_cleanup()
+_async_client_cleanup_registered = True
+
 # Eager loading for backwards compatibility with VCR and other HTTP recording tools
 # When LITELLM_DISABLE_LAZY_LOADING is set, lazy-loaded attributes are loaded at import time
 # For now, this only affects encoding (tiktoken) as it was the only reported issue
@@ -1663,13 +1672,6 @@ if os.getenv("LITELLM_DISABLE_LAZY_LOADING", "").lower() in ("1", "true", "yes",
 
 def __getattr__(name: str) -> Any:
     """Lazy import handler with cached registry for improved performance."""
-    global _async_client_cleanup_registered
-    # Register async client cleanup on first access (only once)
-    if not _async_client_cleanup_registered:
-        from litellm.llms.custom_httpx.async_client_cleanup import register_async_client_cleanup
-        register_async_client_cleanup()
-        _async_client_cleanup_registered = True
-
     # Use cached registry from _lazy_imports instead of importing tuples every time
     from ._lazy_imports import _get_lazy_import_registry
 

tests/test_litellm/llms/custom_httpx/test_gemini_session_leak.py

@@ -118,6 +118,25 @@ async def test_atexit_cleanup():
         return False
 
 
+def test_async_client_cleanup_registered_at_import_time():
+    """
+    Regression test for issue #23278: SSL transport errors with asyncio.gather.
+
+    acompletion is imported at module level via `from .main import *`, so
+    __getattr__ is never triggered when users call litellm.acompletion().
+    register_async_client_cleanup() must be called eagerly at import time,
+    not lazily inside __getattr__, otherwise SSL connections are left open
+    at process exit causing "Fatal error on SSL transport" errors.
+    """
+    import litellm
+
+    assert litellm._async_client_cleanup_registered is True, (
+        "register_async_client_cleanup() must be called at import time. "
+        "If this fails, SSL connections will leak on process exit when "
+        "acompletion() is used with asyncio.gather() (issue #23278)."
+    )
+
+
 def test_new_event_loop_atexit():
     """Test that the new atexit handler can create a fresh event loop"""
     print("\n" + "=" * 70)