[misc] improve model support check in another process (#9208)

docs/requirements-docs.txt

@@ -4,6 +4,7 @@ sphinx-copybutton==0.5.2
 myst-parser==2.0.0
 sphinx-argparse==0.4.0
 msgspec
+cloudpickle
 
 # packages to install to build the documentation
 pydantic >= 2.8

vllm/model_executor/models/registry.py

 import importlib
-import string
+import pickle
 import subprocess
 import sys
-import uuid
+import tempfile
 from functools import lru_cache, partial
 from typing import Callable, Dict, List, Optional, Tuple, Type, Union
 
+import cloudpickle
 import torch.nn as nn
 
 from vllm.logger import init_logger
@@ -282,36 +283,28 @@ class ModelRegistry:
 
             raise
 
-        valid_name_characters = string.ascii_letters + string.digits + "._"
-        if any(s not in valid_name_characters for s in mod_name):
-            raise ValueError(f"Unsafe module name detected for {model_arch}")
-        if any(s not in valid_name_characters for s in cls_name):
-            raise ValueError(f"Unsafe class name detected for {model_arch}")
-        if any(s not in valid_name_characters for s in func.__module__):
-            raise ValueError(f"Unsafe module name detected for {func}")
-        if any(s not in valid_name_characters for s in func.__name__):
-            raise ValueError(f"Unsafe class name detected for {func}")
-
-        err_id = uuid.uuid4()
-
-        stmts = ";".join([
-            f"from {mod_name} import {cls_name}",
-            f"from {func.__module__} import {func.__name__}",
-            f"assert {func.__name__}({cls_name}), '{err_id}'",
-        ])
-
-        result = subprocess.run([sys.executable, "-c", stmts],
+        with tempfile.NamedTemporaryFile() as output_file:
+            # `cloudpickle` allows pickling lambda functions directly
+            input_bytes = cloudpickle.dumps(
+                (mod_name, cls_name, func, output_file.name))
+            # cannot use `sys.executable __file__` here because the script
+            # contains relative imports
+            returned = subprocess.run(
+                [sys.executable, "-m", "vllm.model_executor.models.registry"],
+                input=input_bytes,
                 capture_output=True)
 
-        if result.returncode != 0:
-            err_lines = [line.decode() for line in result.stderr.splitlines()]
-            if err_lines and err_lines[-1] != f"AssertionError: {err_id}":
-                err_str = "\n".join(err_lines)
-                raise RuntimeError(
-                    "An unexpected error occurred while importing the model in "
-                    f"another process. Error log:\n{err_str}")
-
-        return result.returncode == 0
+            # check if the subprocess is successful
+            try:
+                returned.check_returncode()
+            except Exception as e:
+                # wrap raised exception to provide more information
+                raise RuntimeError(f"Error happened when testing "
+                                   f"model support for{mod_name}.{cls_name}:\n"
+                                   f"{returned.stderr.decode()}") from e
+            with open(output_file.name, "rb") as f:
+                result = pickle.load(f)
+            return result
 
     @staticmethod
     def is_text_generation_model(architectures: Union[str, List[str]]) -> bool:
@@ -364,3 +357,13 @@ class ModelRegistry:
                         default=False)
 
         return any(is_pp(arch) for arch in architectures)
+
+
+if __name__ == "__main__":
+    (mod_name, cls_name, func,
+     output_file) = pickle.loads(sys.stdin.buffer.read())
+    mod = importlib.import_module(mod_name)
+    klass = getattr(mod, cls_name)
+    result = func(klass)
+    with open(output_file, "wb") as f:
+        f.write(pickle.dumps(result))