fix: Add __mp_main__ as a duplicate for __main__ for pickle to work

Signed-off-by: yihong0618 <zouzou0208@gmail.com>

Author: yihong0618

Lib/profiling/sampling/_sync_coordinator.py

@@ -10,6 +10,7 @@
 import socket
 import runpy
 import time
+import types
 from typing import List, NoReturn
 
 
@@ -176,9 +177,15 @@ def _execute_script(script_path: str, script_args: List[str], cwd: str) -> None:
         with open(script_path, 'rb') as f:
             source_code = f.read()
 
-        # Compile and execute the script
+        # gh-140729: Create a __mp_main__ module to allow pickling
+        main_module = types.ModuleType("__main__")
+        main_module.__file__ = script_path
+        main_module.__builtins__ = __builtins__
+        sys.modules['__main__'] = sys.modules['__mp_main__'] = main_module
+
         code = compile(source_code, script_path, 'exec')
-        exec(code, {'__name__': '__main__', '__file__': script_path})
+        exec(code, main_module.__dict__)
+
     except FileNotFoundError as e:
         raise TargetError(f"Script file not found: {script_path}") from e
     except PermissionError as e:

Lib/test/test_profiling/test_sampling_profiler.py

@@ -2991,5 +2991,49 @@ def test_parse_mode_function(self):
             profiling.sampling.sample._parse_mode("invalid")
 
 
+@requires_subprocess()
+@skip_if_not_supported
+class TestProcessPoolExecutorSupport(unittest.TestCase):
+    """
+    Test that ProcessPoolExecutor works correctly with profiling.sampling.
+    """
+
+    def test_process_pool_executor_pickle(self):
+        # gh-140729: test use ProcessPoolExecutor.map() can sampling
+        test_script = '''
+import concurrent.futures
+
+def worker(x):
+    return x * 2
+
+if __name__ == "__main__":
+    with concurrent.futures.ProcessPoolExecutor() as executor:
+        results = list(executor.map(worker, [1, 2, 3]))
+        print(f"Results: {results}")
+'''
+        with tempfile.NamedTemporaryFile(
+            mode='w', suffix='.py', delete=False
+        ) as script_file:
+            script_file.write(test_script)
+            script_file.flush()
+            script_name = script_file.name
+
+        result = subprocess.run(
+            [
+                sys.executable,
+                "-m", "profiling.sampling.sample",
+                "-d", "1",
+                "-i", "100000",
+                script_name
+            ],
+            capture_output=True,
+            text=True,
+            timeout=10
+        )
+
+        self.assertIn("Results: [2, 4, 6]", result.stdout)
+        self.assertNotIn("Can't pickle", result.stderr)
+
+
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS.d/next/Core_and_Builtins/2025-10-29-11-31-59.gh-issue-140729.t9JsNt.rst

@@ -0,0 +1,2 @@
+Fix: Add __mp_main__ as a duplicate for __main__ for pickle to work in
+sampling