From: Stanley <46876382+slateny@users.noreply.github.com>
Date: Sun, 16 Oct 2022 17:04:43 +0000 (-0700)
Subject: gh-85299: Add note warning about entry point guard for asyncio example (#93457)
X-Git-Tag: v3.12.0a1~91
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=79fd6ccdbe00ec95e4d33fc24fe76076282a334e;p=thirdparty%2FPython%2Fcpython.git

gh-85299: Add note warning about entry point guard for asyncio example (#93457)
---

diff --git a/Doc/library/asyncio-eventloop.rst b/Doc/library/asyncio-eventloop.rst
index 2f306b7edb8f..4f12074dd700 100644
--- a/Doc/library/asyncio-eventloop.rst
+++ b/Doc/library/asyncio-eventloop.rst
@@ -1253,7 +1253,13 @@ Executing code in thread or process pools
                   pool, cpu_bound)
               print('custom process pool', result)
 
-      asyncio.run(main())
+      if __name__ == '__main__':
+          asyncio.run(main())
+
+   Note that the entry point guard (``if __name__ == '__main__'``)
+   is required for option 3 due to the peculiarities of :mod:`multiprocessing`,
+   which is used by :class:`~concurrent.futures.ProcessPoolExecutor`.
+   See :ref:`Safe importing of main module <multiprocessing-safe-main-import>`.
 
    This method returns a :class:`asyncio.Future` object.
 
diff --git a/Doc/library/multiprocessing.rst b/Doc/library/multiprocessing.rst
index dab115acdc20..551608478067 100644
--- a/Doc/library/multiprocessing.rst
+++ b/Doc/library/multiprocessing.rst
@@ -2954,6 +2954,8 @@ Global variables
     However, global variables which are just module level constants cause no
     problems.
 
+.. _multiprocessing-safe-main-import:
+
 Safe importing of main module
 
     Make sure that the main module can be safely imported by a new Python