Add a test

Author: YvesDup

Lib/test/test_thread.py

@@ -345,6 +345,47 @@ def func():
             handle = thread.start_joinable_thread(func, handle=None)
             handle.join()
 
+class StartNewThreadKwargsRace(unittest.TestCase):
+
+    @unittest.skipUnless(support.Py_GIL_DISABLED, "GIL must be disabled")
+    def test_dict_growsup_when_thread_start(self):
+        # See gh-149816 - (62) Concurrent kwargs growth causes heap overwrite
+        # This test is meant to be run under a free-threaded build, where the GIL is
+        # disabled and concurrent mutations of the same dict can cause heap
+        # corruption.
+        results = []
+        def mutator(shared, stop, prefix, burst):
+            i = 0
+            while not stop.locked():
+                for _ in range(burst):
+                    shared[f"{prefix}_{i}"] = i
+                    i += 1
+                time.sleep(0)
+            results.append(prefix)
+
+        def nop(i, **kwargs):
+            pass
+
+        stop = thread.lock()
+        shared = {f"base_{i}": i for i in range(20000)}
+        n = 4
+        for i in range(n):
+            args=(shared, stop, f"dynamic_{i}", 1000)
+            thread.start_new_thread(mutator, args)
+
+        snt = 32
+        for i in range(snt):
+            try:
+                thread.start_new_thread(nop, (i,), shared)
+            except RuntimeError:
+                break
+
+        stop.acquire()
+        # wait for all mutator threads stop.
+        wait_t = time.monotonic()
+        while len(results) < n and time.monotonic() - wait_t < 5.0:
+            time.sleep(0.1)
+
 
 class Barrier:
     def __init__(self, num_threads):