From ad2581567da6d66dca3d18ea176cad1040323471 Mon Sep 17 00:00:00 2001
From: Irit Katriel <iritkatriel@yahoo.com>
Date: Mon, 30 May 2022 22:38:58 +0100
Subject: [PATCH 1/2] gh-83658: make multiprocessing.Pool raise an exception if
 maxtasksperchild is not None or a positive int

---
 Lib/multiprocessing/pool.py       | 3 +++
 Lib/test/_test_multiprocessing.py | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/Lib/multiprocessing/pool.py b/Lib/multiprocessing/pool.py
index bbe05a550c349c..961d7e5991847a 100644
--- a/Lib/multiprocessing/pool.py
+++ b/Lib/multiprocessing/pool.py
@@ -203,6 +203,9 @@ def __init__(self, processes=None, initializer=None, initargs=(),
             processes = os.cpu_count() or 1
         if processes < 1:
             raise ValueError("Number of processes must be at least 1")
+        if maxtasksperchild is not None:
+            if not isinstance(maxtasksperchild, int) or maxtasksperchild <= 0:
+                raise ValueError("maxtasksperchild must be a positive int or None")
 
         if initializer is not None and not callable(initializer):
             raise TypeError('initializer must be a callable')
diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py
index 67bb17c0ede364..04e0b1c32015b8 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -2860,6 +2860,11 @@ def test_pool_worker_lifetime_early_close(self):
         for (j, res) in enumerate(results):
             self.assertEqual(res.get(), sqr(j))
 
+    def test_pool_maxtasksperchild_invalid(self):
+        for value in [0, -1, 0.5, "12"]:
+            with self.assertRaises(ValueError):
+                multiprocessing.Pool(3, maxtasksperchild=value)
+
     def test_worker_finalization_via_atexit_handler_of_multiprocessing(self):
         # tests cases against bpo-38744 and bpo-39360
         cmd = '''if 1:

From 71f64d4e22facee77d00b387dc3b6ee5e9ad2954 Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com>
Date: Mon, 30 May 2022 21:42:51 +0000
Subject: [PATCH 2/2] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20blu?=
 =?UTF-8?q?rb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../next/Library/2022-05-30-21-42-50.gh-issue-83658.01Ntx0.rst   | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Library/2022-05-30-21-42-50.gh-issue-83658.01Ntx0.rst

diff --git a/Misc/NEWS.d/next/Library/2022-05-30-21-42-50.gh-issue-83658.01Ntx0.rst b/Misc/NEWS.d/next/Library/2022-05-30-21-42-50.gh-issue-83658.01Ntx0.rst
new file mode 100644
index 00000000000000..a1873095409803
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-05-30-21-42-50.gh-issue-83658.01Ntx0.rst
@@ -0,0 +1 @@
+Make :class:`multiprocessing.Pool` raise an exception if ``maxtasksperchild`` is not ``None`` or a positive int.