From 42aa3cc2bc3c81aa0057dacfdd9a2d344dc7b3cb Mon Sep 17 00:00:00 2001
From: Steve Dower <steve.dower@python.org>
Date: Wed, 19 Oct 2022 20:01:06 +0100
Subject: [PATCH] gh-98360: multiprocessing now spawns children on Windows with
 correct argv[0] in virtual environments

---
 Lib/test/_test_venv_multiprocessing.py        | 40 +++++++++++++++++++
 ...2-10-19-20-00-28.gh-issue-98360.O2m6YG.rst |  4 ++
 2 files changed, 44 insertions(+)
 create mode 100644 Lib/test/_test_venv_multiprocessing.py
 create mode 100644 Misc/NEWS.d/next/Windows/2022-10-19-20-00-28.gh-issue-98360.O2m6YG.rst

diff --git a/Lib/test/_test_venv_multiprocessing.py b/Lib/test/_test_venv_multiprocessing.py
new file mode 100644
index 00000000000000..af72e915ba52bb
--- /dev/null
+++ b/Lib/test/_test_venv_multiprocessing.py
@@ -0,0 +1,40 @@
+import multiprocessing
+import random
+import sys
+import time
+
+def fill_queue(queue, code):
+    queue.put(code)
+
+
+def drain_queue(queue, code):
+    if code != queue.get():
+        sys.exit(1)
+
+
+def test_func():
+    code = random.randrange(0, 1000)
+    queue = multiprocessing.Queue()
+    fill_pool = multiprocessing.Process(
+        target=fill_queue,
+        args=(queue, code)
+    )
+    drain_pool = multiprocessing.Process(
+        target=drain_queue,
+        args=(queue, code)
+    )
+    drain_pool.start()
+    fill_pool.start()
+    fill_pool.join()
+    drain_pool.join()
+
+
+def main():
+    test_pool = multiprocessing.Process(target=test_func)
+    test_pool.start()
+    test_pool.join()
+    sys.exit(test_pool.exitcode)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/Misc/NEWS.d/next/Windows/2022-10-19-20-00-28.gh-issue-98360.O2m6YG.rst b/Misc/NEWS.d/next/Windows/2022-10-19-20-00-28.gh-issue-98360.O2m6YG.rst
new file mode 100644
index 00000000000000..61c1e5e837fe3e
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2022-10-19-20-00-28.gh-issue-98360.O2m6YG.rst
@@ -0,0 +1,4 @@
+Fixes :mod:`multiprocessing` spawning child processes on Windows from a
+virtual environment to ensure that child processes that also use
+:mod:`multiprocessing` to spawn more children will recognize that they are
+in a virtual environment.