From ad1dc3ebb6aadaeeeacde13d4ed2d62bf302bf62 Mon Sep 17 00:00:00 2001
From: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>
Date: Tue, 25 Oct 2022 01:51:42 +0530
Subject: GH-89237: fix hang in proactor `subprocess.wait_closed()` (#98572)

---
 Lib/asyncio/proactor_events.py                                     | 4 +++-
 Lib/test/test_asyncio/test_proactor_events.py                      | 7 ++++++-
 .../next/Library/2022-10-23-18-30-39.gh-issue-89237.kBui30.rst     | 1 +
 3 files changed, 10 insertions(+), 2 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2022-10-23-18-30-39.gh-issue-89237.kBui30.rst

diff --git a/Lib/asyncio/proactor_events.py b/Lib/asyncio/proactor_events.py
index ddb9dac..2685a33 100644
--- a/Lib/asyncio/proactor_events.py
+++ b/Lib/asyncio/proactor_events.py
@@ -60,6 +60,7 @@ class _ProactorBasePipeTransport(transports._FlowControlMixin,
         self._pending_write = 0
         self._conn_lost = 0
         self._closing = False  # Set when close() called.
+        self._called_connection_lost = False
         self._eof_written = False
         if self._server is not None:
             self._server._attach()
@@ -136,7 +137,7 @@ class _ProactorBasePipeTransport(transports._FlowControlMixin,
                 self._empty_waiter.set_result(None)
             else:
                 self._empty_waiter.set_exception(exc)
-        if self._closing:
+        if self._closing and self._called_connection_lost:
             return
         self._closing = True
         self._conn_lost += 1
@@ -166,6 +167,7 @@ class _ProactorBasePipeTransport(transports._FlowControlMixin,
             if server is not None:
                 server._detach()
                 self._server = None
+            self._called_connection_lost = True
 
     def get_write_buffer_size(self):
         size = self._pending_write
diff --git a/Lib/test/test_asyncio/test_proactor_events.py b/Lib/test/test_asyncio/test_proactor_events.py
index 7fca054..7fd8b26 100644
--- a/Lib/test/test_asyncio/test_proactor_events.py
+++ b/Lib/test/test_asyncio/test_proactor_events.py
@@ -290,7 +290,12 @@ class ProactorSocketTransportTests(test_utils.TestCase):
         tr._closing = True
         tr._force_close(None)
         test_utils.run_briefly(self.loop)
-        self.assertFalse(self.protocol.connection_lost.called)
+        # See https://github.com/python/cpython/issues/89237
+        # `protocol.connection_lost` should be called even if
+        # the transport was closed forcefully otherwise
+        # the resources held by protocol will never be freed
+        # and waiters will never be notified leading to hang.
+        self.assertTrue(self.protocol.connection_lost.called)
 
     def test_fatal_error_2(self):
         tr = self.socket_transport()
diff --git a/Misc/NEWS.d/next/Library/2022-10-23-18-30-39.gh-issue-89237.kBui30.rst b/Misc/NEWS.d/next/Library/2022-10-23-18-30-39.gh-issue-89237.kBui30.rst
new file mode 100644
index 0000000..668ea4c
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-10-23-18-30-39.gh-issue-89237.kBui30.rst
@@ -0,0 +1 @@
+Fix hang on Windows in ``subprocess.wait_closed()`` in :mod:`asyncio` with :class:`~asyncio.ProactorEventLoop`. Patch by Kumar Aditya.
-- 
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