Don't actually import module when checking if its valid (#136548)

ezyang · pytorchmergebot · commit 76b044d7cb98 · 2024-09-25T20:47:32.000Z
Summary: If you actually import the module, you might end up with some import cycle situation where a module is imported too early and accesses things that are not initialized yet. Test Plan: sandcastle and ossci ``` TORCH_LOGS=+torch._inductor.codecache buck run mode/opt caffe2/benchmarks/dynamo:torchbench ``` Differential Revision: D63330224 Pull Request resolved: #136548 Approved by: https://github.com/Skylion007
diff --git a/torch/_logging/_internal.py b/torch/_logging/_internal.py
@@ -1,6 +1,7 @@
 # mypy: allow-untyped-defs
 import functools
 import hashlib
+import importlib.util
 import itertools
 import json
 import logging
@@ -13,7 +14,6 @@
 import time
 from collections import defaultdict
 from dataclasses import dataclass, field
-from importlib import __import__
 from typing import Any, Callable, Dict, List, Optional, Set, Tuple, Union
 from weakref import WeakSet
 
@@ -724,11 +724,8 @@ def get_name_level_pair(name):
 
 
 def _is_valid_module(qname):
-    try:
-        __import__(qname)
-        return True
-    except ImportError:
-        return False
+    spec = importlib.util.find_spec(qname)
+    return spec is not None
 
 
 def _update_log_state_from_env():
