bpo-44645: Check for interrupts on any potentially backwards edge (GH-27216)

1 files changed, 25 insertions, 0 deletions

diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index f648a8b2bc..23fe2d3f4d 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]
+        interrupted = [False]
+
+        def worker(started, cont, interrupted):
+            iterations = 100_000_000
+            started[0] = True
+            while cont[0]:
+                if iterations:
+                    iterations -= 1
+                else:
+                    return
+                pass
+            interrupted[0] = True
+
+        t = threading.Thread(target=worker,args=(started, cont, interrupted))
+        t.start()
+        while not started[0]:
+            pass
+        cont[0] = False
+        t.join()
+        self.assertTrue(interrupted[0])
+
 
 class AtexitTests(unittest.TestCase):