[pull] main from python:main

.github/CODEOWNERS

@@ -80,9 +80,10 @@ Tools/patchcheck/             @AA-Turner
 # ----------------------------------------------------------------------------
 
 # Autotools
-configure*                       @erlend-aasland @corona10 @AA-Turner
-Makefile.pre.in                  @erlend-aasland @AA-Turner
-Modules/Setup*                   @erlend-aasland @AA-Turner
+configure*                       @erlend-aasland @corona10 @AA-Turner @emmatyping
+Makefile.pre.in                  @erlend-aasland @AA-Turner @emmatyping
+Modules/Setup*                   @erlend-aasland @AA-Turner @emmatyping
+Modules/makesetup                @emmatyping
 Tools/build/regen-configure.sh   @AA-Turner
 
 
@@ -157,16 +158,16 @@ Lib/_osx_support.py           @python/macos-team
 Lib/test/test__osx_support.py @python/macos-team
 
 # WebAssembly
-Tools/wasm/README.md          @brettcannon @freakboy3742
+Tools/wasm/README.md          @brettcannon @freakboy3742 @emmatyping
 
 # WebAssembly (Emscripten)
-Tools/wasm/config.site-wasm32-emscripten  @freakboy3742
-Tools/wasm/emscripten                     @freakboy3742
+Tools/wasm/config.site-wasm32-emscripten  @freakboy3742 @emmatyping
+Tools/wasm/emscripten                     @freakboy3742 @emmatyping
 
 # WebAssembly (WASI)
-Tools/wasm/wasi-env           @brettcannon
-Tools/wasm/wasi.py            @brettcannon
-Tools/wasm/wasi               @brettcannon
+Tools/wasm/wasi-env           @brettcannon @emmatyping
+Tools/wasm/wasi.py            @brettcannon @emmatyping
+Tools/wasm/wasi               @brettcannon @emmatyping
 
 # Windows
 PC/                           @python/windows-team
@@ -603,9 +604,9 @@ Lib/test/test_zipfile/_path/  @jaraco
 Lib/zipfile/_path/            @jaraco
 
 # Zstandard
-Lib/compression/zstd/         @AA-Turner
-Lib/test/test_zstd.py         @AA-Turner
-Modules/_zstd/                @AA-Turner
+Lib/compression/zstd/         @AA-Turner @emmatyping
+Lib/test/test_zstd.py         @AA-Turner @emmatyping
+Modules/_zstd/                @AA-Turner @emmatyping
 
 # ----------------------------------------------------------------------------
 

Lib/multiprocessing/forkserver.py

@@ -145,12 +145,13 @@ def ensure_running(self):
             cmd = ('from multiprocessing.forkserver import main; ' +
                    'main(%d, %d, %r, **%r)')
 
+            main_kws = {}
             if self._preload_modules:
-                desired_keys = {'main_path', 'sys_path'}
                 data = spawn.get_preparation_data('ignore')
-                main_kws = {x: y for x, y in data.items() if x in desired_keys}
-            else:
-                main_kws = {}
+                if 'sys_path' in data:
+                    main_kws['sys_path'] = data['sys_path']
+                if 'init_main_from_path' in data:
+                    main_kws['main_path'] = data['init_main_from_path']
 
             with socket.socket(socket.AF_UNIX) as listener:
                 address = connection.arbitrary_address('AF_UNIX')

Lib/multiprocessing/popen_spawn_posix.py

@@ -57,6 +57,10 @@ def _launch(self, process_obj):
             self._fds.extend([child_r, child_w])
             self.pid = util.spawnv_passfds(spawn.get_executable(),
                                            cmd, self._fds)
+            os.close(child_r)
+            child_r = None
+            os.close(child_w)
+            child_w = None
             self.sentinel = parent_r
             with open(parent_w, 'wb', closefd=False) as f:
                 f.write(fp.getbuffer())

Lib/test/_test_multiprocessing.py

@@ -7028,6 +7028,18 @@ def child():
         self.assertEqual(q.get_nowait(), "done")
         close_queue(q)
 
+    def test_preload_main(self):
+        # gh-126631: Check that __main__ can be pre-loaded
+        if multiprocessing.get_start_method() != "forkserver":
+            self.skipTest("forkserver specific test")
+
+        name = os.path.join(os.path.dirname(__file__), 'mp_preload_main.py')
+        _, out, err = test.support.script_helper.assert_python_ok(name)
+        self.assertEqual(err, b'')
+
+        # The trailing empty string comes from split() on output ending with \n
+        out = out.decode().split("\n")
+        self.assertEqual(out, ['__main__', '__mp_main__', 'f', 'f', ''])
 
 #
 # Mixins

Lib/test/list_tests.py

@@ -32,13 +32,13 @@ def test_init(self):
         self.assertEqual(a, b)
 
     def test_getitem_error(self):
-        a = []
+        a = self.type2test([])
         msg = "list indices must be integers or slices"
         with self.assertRaisesRegex(TypeError, msg):
             a['a']
 
     def test_setitem_error(self):
-        a = []
+        a = self.type2test([])
         msg = "list indices must be integers or slices"
         with self.assertRaisesRegex(TypeError, msg):
             a['a'] = "python"
@@ -561,7 +561,7 @@ def test_constructor_exception_handling(self):
         class F(object):
             def __iter__(self):
                 raise KeyboardInterrupt
-        self.assertRaises(KeyboardInterrupt, list, F())
+        self.assertRaises(KeyboardInterrupt, self.type2test, F())
 
     def test_exhausted_iterator(self):
         a = self.type2test([1, 2, 3])

Lib/test/mp_preload_main.py

@@ -0,0 +1,14 @@
+import multiprocessing
+
+print(f"{__name__}")
+
+def f():
+    print("f")
+
+if __name__ == "__main__":
+    ctx = multiprocessing.get_context("forkserver")
+    ctx.set_forkserver_preload(['__main__'])
+    for _ in range(2):
+        p = ctx.Process(target=f)
+        p.start()
+        p.join()

Misc/NEWS.d/next/Library/2024-05-13-09-50-31.gh-issue-118981.zgOQPv.rst

@@ -0,0 +1,2 @@
+Fix potential hang in ``multiprocessing.popen_spawn_posix`` that can happen
+when the child proc dies early by closing the child fds right away.

Misc/NEWS.d/next/Library/2025-06-10-21-00-48.gh-issue-126631.eITVJd.rst

@@ -0,0 +1,2 @@
+Fix :mod:`multiprocessing` ``forkserver`` bug which prevented ``__main__``
+from being preloaded.