GH-66285: Revert "fix forking in asyncio" (#99756)

Author: kumaraditya303

Lib/asyncio/events.py

@@ -17,7 +17,6 @@
 import subprocess
 import sys
 import threading
-import signal
 
 from . import format_helpers
 
@@ -666,14 +665,6 @@ class _Local(threading.local):
 
     def __init__(self):
         self._local = self._Local()
-        if hasattr(os, 'fork'):
-            def on_fork():
-                # Reset the loop and wakeupfd in the forked child process.
-                self._local = self._Local()
-                signal.set_wakeup_fd(-1)
-
-            os.register_at_fork(after_in_child=on_fork)
-
 
     def get_event_loop(self):
         """Get the event loop for the current context.

Lib/test/test_asyncio/test_unix_events.py

@@ -11,14 +11,10 @@
 import sys
 import threading
 import unittest
-import time
 from unittest import mock
 import warnings
-import multiprocessing
 from test.support import os_helper
 from test.support import socket_helper
-from test.support import wait_process
-from test.support import hashlib_helper
 
 if sys.platform == 'win32':
     raise unittest.SkipTest('UNIX only')
@@ -1871,100 +1867,5 @@ async def runner():
             wsock.close()
 
 
-@unittest.skipUnless(hasattr(os, 'fork'), 'requires os.fork()')
-class TestFork(unittest.IsolatedAsyncioTestCase):
-
-    async def test_fork_not_share_event_loop(self):
-        # The forked process should not share the event loop with the parent
-        loop = asyncio.get_running_loop()
-        r, w = os.pipe()
-        self.addCleanup(os.close, r)
-        self.addCleanup(os.close, w)
-        pid = os.fork()
-        if pid == 0:
-            # child
-            try:
-                loop = asyncio.get_event_loop_policy().get_event_loop()
-                os.write(w, str(id(loop)).encode())
-            finally:
-                os._exit(0)
-        else:
-            # parent
-            child_loop = int(os.read(r, 100).decode())
-            self.assertNotEqual(child_loop, id(loop))
-            wait_process(pid, exitcode=0)
-
-    @hashlib_helper.requires_hashdigest('md5')
-    def test_fork_signal_handling(self):
-        # Sending signal to the forked process should not affect the parent
-        # process
-        ctx = multiprocessing.get_context('fork')
-        manager = ctx.Manager()
-        self.addCleanup(manager.shutdown)
-        child_started = manager.Event()
-        child_handled = manager.Event()
-        parent_handled = manager.Event()
-
-        def child_main():
-            signal.signal(signal.SIGTERM, lambda *args: child_handled.set())
-            child_started.set()
-            time.sleep(1)
-
-        async def main():
-            loop = asyncio.get_running_loop()
-            loop.add_signal_handler(signal.SIGTERM, lambda *args: parent_handled.set())
-
-            process = ctx.Process(target=child_main)
-            process.start()
-            child_started.wait()
-            os.kill(process.pid, signal.SIGTERM)
-            process.join()
-
-            async def func():
-                await asyncio.sleep(0.1)
-                return 42
-
-            # Test parent's loop is still functional
-            self.assertEqual(await asyncio.create_task(func()), 42)
-
-        asyncio.run(main())
-
-        self.assertFalse(parent_handled.is_set())
-        self.assertTrue(child_handled.is_set())
-
-    @hashlib_helper.requires_hashdigest('md5')
-    def test_fork_asyncio_run(self):
-        ctx = multiprocessing.get_context('fork')
-        manager = ctx.Manager()
-        self.addCleanup(manager.shutdown)
-        result = manager.Value('i', 0)
-
-        async def child_main():
-            await asyncio.sleep(0.1)
-            result.value = 42
-
-        process = ctx.Process(target=lambda: asyncio.run(child_main()))
-        process.start()
-        process.join()
-
-        self.assertEqual(result.value, 42)
-
-    @hashlib_helper.requires_hashdigest('md5')
-    def test_fork_asyncio_subprocess(self):
-        ctx = multiprocessing.get_context('fork')
-        manager = ctx.Manager()
-        self.addCleanup(manager.shutdown)
-        result = manager.Value('i', 1)
-
-        async def child_main():
-            proc = await asyncio.create_subprocess_exec(sys.executable, '-c', 'pass')
-            result.value = await proc.wait()
-
-        process = ctx.Process(target=lambda: asyncio.run(child_main()))
-        process.start()
-        process.join()
-
-        self.assertEqual(result.value, 0)
-
 if __name__ == '__main__':
     unittest.main()