[FRONTEND] Ensure version_key is called at most once (#519)

Co-authored-by: hauntsaninja <>

python/triton/code_gen.py

@@ -11,6 +11,7 @@ import subprocess
 import sys
 import tempfile
 import textwrap
+import threading
 import time
 import warnings
 from typing import Dict, Set, Tuple, Union
@@ -1058,27 +1059,40 @@ class Autotuner:
         return self.kernel(*args, num_warps=config.num_warps, num_stages=config.num_stages, **kwargs, **config.kwargs)
 
 
-@functools.lru_cache()
+_version_key_lock = threading.Lock()
+_version_key = None
+
+
 def version_key():
-    import pkgutil
-    contents = []
-    # frontend
-    with open(triton.code_gen.__file__, "rb") as f:
-        contents += [hashlib.md5(f.read()).hexdigest()]
-    # backend
-    with open(triton._C.libtriton.__file__, "rb") as f:
-        contents += [hashlib.md5(f.read()).hexdigest()]
-    # language
-    language_path = os.path.join(*triton.__path__, 'language')
-    for lib in pkgutil.iter_modules([language_path]):
-        with open(lib.module_finder.find_spec(lib.name).origin, "rb") as f:
+    global _version_key
+
+    if _version_key is not None:
+        return _version_key
+
+    with _version_key_lock:
+        if _version_key is not None:
+            return _version_key
+
+        import pkgutil
+        contents = []
+        # frontend
+        with open(triton.code_gen.__file__, "rb") as f:
             contents += [hashlib.md5(f.read()).hexdigest()]
-    # ptxas version
-    try:
-        ptxas_version = hashlib.md5(subprocess.check_output(["ptxas", "--version"])).hexdigest()
-    except Exception:
-        ptxas_version = ''
-    return '-'.join(triton.__version__) + '-' + ptxas_version + '-' + '-'.join(contents)
+        # backend
+        with open(triton._C.libtriton.__file__, "rb") as f:
+            contents += [hashlib.md5(f.read()).hexdigest()]
+        # language
+        language_path = os.path.join(*triton.__path__, 'language')
+        for lib in pkgutil.iter_modules([language_path]):
+            with open(lib.module_finder.find_spec(lib.name).origin, "rb") as f:
+                contents += [hashlib.md5(f.read()).hexdigest()]
+        # ptxas version
+        try:
+            ptxas_version = hashlib.md5(subprocess.check_output(["ptxas", "--version"])).hexdigest()
+        except Exception:
+            ptxas_version = ''
+        _version_key = '-'.join(triton.__version__) + '-' + ptxas_version + '-' + '-'.join(contents)
+        return _version_key
 
 
 class DependenciesFinder(ast.NodeVisitor):