gh-103847: fix some asyncio subprocess cancellation bugs (GH-146571)

(cherry picked from commit f429fb3)

Co-authored-by: Kumar Aditya <kumaraditya@python.org>

Author: kumaraditya303

Lib/asyncio/base_subprocess.py

@@ -22,7 +22,7 @@ def __init__(self, loop, protocol, args, shell,
         self._proc = None
         self._pid = None
         self._returncode = None
-        self._exit_waiters = []
+        self._exit_waiters = set()
         self._pending_calls = collections.deque()
         self._pipes = {}
         self._finished = False
@@ -211,6 +211,14 @@ async def _connect_pipes(self, waiter):
         except (SystemExit, KeyboardInterrupt):
             raise
         except BaseException as exc:
+            # Close any pipes that were already connected before the
+            # error/cancellation to avoid leaking file descriptors.
+            for proto in self._pipes.values():
+                if proto is not None:
+                    proto.pipe.close()
+            for raw_pipe in (proc.stdin, proc.stdout, proc.stderr):
+                if raw_pipe is not None:
+                    raw_pipe.close()
             if waiter is not None and not waiter.cancelled():
                 waiter.set_exception(exc)
         else:
@@ -260,8 +268,12 @@ async def _wait(self):
             return self._returncode
 
         waiter = self._loop.create_future()
-        self._exit_waiters.append(waiter)
-        return await waiter
+        self._exit_waiters.add(waiter)
+        try:
+            return await waiter
+        finally:
+            if self._exit_waiters is not None:
+                self._exit_waiters.discard(waiter)
 
     def _try_finish(self):
         assert not self._finished

Lib/asyncio/unix_events.py

@@ -212,7 +212,7 @@ async def _make_subprocess_transport(self, protocol, args, shell,
             raise
         except BaseException:
             transp.close()
-            await transp._wait()
+            await tasks.shield(transp._wait())
             raise
 
         return transp

Lib/asyncio/windows_events.py

@@ -408,7 +408,7 @@ async def _make_subprocess_transport(self, protocol, args, shell,
             raise
         except BaseException:
             transp.close()
-            await transp._wait()
+            await tasks.shield(transp._wait())
             raise
 
         return transp

Lib/test/test_asyncio/test_subprocess.py

@@ -11,7 +11,7 @@
 from asyncio import subprocess
 from test.test_asyncio import utils as test_utils
 from test import support
-from test.support import os_helper, warnings_helper, gc_collect
+from test.support import os_helper, gc_collect
 
 if not support.has_subprocess_support:
     raise unittest.SkipTest("test module requires subprocess")
@@ -919,7 +919,6 @@ async def main():
 
         self.loop.run_until_complete(main())
 
-    @warnings_helper.ignore_warnings(category=ResourceWarning)
     def test_subprocess_read_pipe_cancelled(self):
         async def main():
             loop = asyncio.get_running_loop()
@@ -930,7 +929,6 @@ async def main():
         asyncio.run(main())
         gc_collect()
 
-    @warnings_helper.ignore_warnings(category=ResourceWarning)
     def test_subprocess_write_pipe_cancelled(self):
         async def main():
             loop = asyncio.get_running_loop()
@@ -941,7 +939,6 @@ async def main():
         asyncio.run(main())
         gc_collect()
 
-    @warnings_helper.ignore_warnings(category=ResourceWarning)
     def test_subprocess_read_write_pipe_cancelled(self):
         async def main():
             loop = asyncio.get_running_loop()