From 000e70ad5246732fcbd27cf59268185cbd5ad734 Mon Sep 17 00:00:00 2001
From: Mark Shannon <mark@hotpy.org>
Date: Fri, 16 Jul 2021 10:59:31 +0100
Subject: bpo-44645: Check for interrupts on any potentially backwards edge.
 (GH-27167)

---
 Lib/test/test_threading.py | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

(limited to 'Lib/test/test_threading.py')

diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index f648a8b2bc5..3b5bc42357e 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -1604,6 +1604,31 @@ class InterruptMainTests(unittest.TestCase):
         self.assertRaises(ValueError, _thread.interrupt_main, signal.NSIG)
         self.assertRaises(ValueError, _thread.interrupt_main, 1000000)
 
+    @threading_helper.reap_threads
+    def test_can_interrupt_tight_loops(self):
+        cont = True
+        started = False
+        iterations = 100_000_000
+
+        def worker():
+            nonlocal iterations
+            nonlocal started
+            started = True
+            while cont:
+                if iterations:
+                    iterations -= 1
+                else:
+                    return
+                pass
+
+        t = threading.Thread(target=worker)
+        t.start()
+        while not started:
+            pass
+        cont = False
+        t.join()
+        self.assertNotEqual(iterations, 0)
+
 
 class AtexitTests(unittest.TestCase):
 
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