3 files changed, 106 insertions, 19 deletions
diff --git a/Lib/test/test_free_threading/test_io.py b/Lib/test/test_free_threading/test_io.py
index f9bec740ddf..41d89e04da8 100644
--- a/Lib/test/test_free_threading/test_io.py
+++ b/Lib/test/test_free_threading/test_io.py
@@ -1,12 +1,13 @@
+import io
+import _pyio as pyio
 import threading
 from unittest import TestCase
 from test.support import threading_helper
 from random import randint
-from io import BytesIO
 from sys import getsizeof
 
 
-class TestBytesIO(TestCase):
+class ThreadSafetyMixin:
     # Test pretty much everything that can break under free-threading.
     # Non-deterministic, but at least one of these things will fail if
     # BytesIO object is not free-thread safe.
@@ -90,20 +91,27 @@ class TestBytesIO(TestCase):
             barrier.wait()
             getsizeof(b)
 
-        self.check([write] * 10, BytesIO())
-        self.check([writelines] * 10, BytesIO())
-        self.check([write] * 10 + [truncate] * 10, BytesIO())
-        self.check([truncate] + [read] * 10, BytesIO(b'0\n'*204800))
-        self.check([truncate] + [read1] * 10, BytesIO(b'0\n'*204800))
-        self.check([truncate] + [readline] * 10, BytesIO(b'0\n'*20480))
-        self.check([truncate] + [readlines] * 10, BytesIO(b'0\n'*20480))
-        self.check([truncate] + [readinto] * 10, BytesIO(b'0\n'*204800), bytearray(b'0\n'*204800))
-        self.check([close] + [write] * 10, BytesIO())
-        self.check([truncate] + [getvalue] * 10, BytesIO(b'0\n'*204800))
-        self.check([truncate] + [getbuffer] * 10, BytesIO(b'0\n'*204800))
-        self.check([truncate] + [iter] * 10, BytesIO(b'0\n'*20480))
-        self.check([truncate] + [getstate] * 10, BytesIO(b'0\n'*204800))
-        self.check([truncate] + [setstate] * 10, BytesIO(b'0\n'*204800), (b'123', 0, None))
-        self.check([truncate] + [sizeof] * 10, BytesIO(b'0\n'*204800))
+        self.check([write] * 10, self.ioclass())
+        self.check([writelines] * 10, self.ioclass())
+        self.check([write] * 10 + [truncate] * 10, self.ioclass())
+        self.check([truncate] + [read] * 10, self.ioclass(b'0\n'*204800))
+        self.check([truncate] + [read1] * 10, self.ioclass(b'0\n'*204800))
+        self.check([truncate] + [readline] * 10, self.ioclass(b'0\n'*20480))
+        self.check([truncate] + [readlines] * 10, self.ioclass(b'0\n'*20480))
+        self.check([truncate] + [readinto] * 10, self.ioclass(b'0\n'*204800), bytearray(b'0\n'*204800))
+        self.check([close] + [write] * 10, self.ioclass())
+        self.check([truncate] + [getvalue] * 10, self.ioclass(b'0\n'*204800))
+        self.check([truncate] + [getbuffer] * 10, self.ioclass(b'0\n'*204800))
+        self.check([truncate] + [iter] * 10, self.ioclass(b'0\n'*20480))
+        self.check([truncate] + [getstate] * 10, self.ioclass(b'0\n'*204800))
+        state = self.ioclass(b'123').__getstate__()
+        self.check([truncate] + [setstate] * 10, self.ioclass(b'0\n'*204800), state)
+        self.check([truncate] + [sizeof] * 10, self.ioclass(b'0\n'*204800))
 
         # no tests for seek or tell because they don't break anything
+
+class CBytesIOTest(ThreadSafetyMixin, TestCase):
+    ioclass = io.BytesIO
+
+class PyBytesIOTest(ThreadSafetyMixin, TestCase):
+     ioclass = pyio.BytesIO
diff --git a/Lib/test/test_free_threading/test_itertools.py b/Lib/test/test_free_threading/test_itertools.py
index b8663ade1d4..9d366041917 100644
--- a/Lib/test/test_free_threading/test_itertools.py
+++ b/Lib/test/test_free_threading/test_itertools.py
@@ -1,6 +1,6 @@
 import unittest
 from threading import Thread, Barrier
-from itertools import batched, cycle
+from itertools import batched, chain, cycle
 from test.support import threading_helper
 
 
@@ -17,7 +17,7 @@ class ItertoolsThreading(unittest.TestCase):
             barrier.wait()
             while True:
                 try:
-                    _ = next(it)
+                    next(it)
                 except StopIteration:
                     break
 
@@ -62,6 +62,34 @@ class ItertoolsThreading(unittest.TestCase):
 
             barrier.reset()
 
+    @threading_helper.reap_threads
+    def test_chain(self):
+        number_of_threads = 6
+        number_of_iterations = 20
+
+        barrier = Barrier(number_of_threads)
+        def work(it):
+            barrier.wait()
+            while True:
+                try:
+                    next(it)
+                except StopIteration:
+                    break
+
+        data = [(1, )] * 200
+        for it in range(number_of_iterations):
+            chain_iterator = chain(*data)
+            worker_threads = []
+            for ii in range(number_of_threads):
+                worker_threads.append(
+                    Thread(target=work, args=[chain_iterator]))
+
+            with threading_helper.start_threads(worker_threads):
+                pass
+
+            barrier.reset()
+
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_free_threading/test_itertools_combinatoric.py b/Lib/test/test_free_threading/test_itertools_combinatoric.py
new file mode 100644
index 00000000000..5b3b88deedd
--- /dev/null
+++ b/Lib/test/test_free_threading/test_itertools_combinatoric.py
@@ -0,0 +1,51 @@
+import unittest
+from threading import Thread, Barrier
+from itertools import combinations, product
+from test.support import threading_helper
+
+
+threading_helper.requires_working_threading(module=True)
+
+def test_concurrent_iteration(iterator, number_of_threads):
+    barrier = Barrier(number_of_threads)
+    def iterator_worker(it):
+        barrier.wait()
+        while True:
+            try:
+                _ = next(it)
+            except StopIteration:
+                return
+
+    worker_threads = []
+    for ii in range(number_of_threads):
+        worker_threads.append(
+            Thread(target=iterator_worker, args=[iterator]))
+
+    with threading_helper.start_threads(worker_threads):
+        pass
+
+    barrier.reset()
+
+class ItertoolsThreading(unittest.TestCase):
+
+    @threading_helper.reap_threads
+    def test_combinations(self):
+        number_of_threads = 10
+        number_of_iterations = 24
+
+        for it in range(number_of_iterations):
+            iterator = combinations((1, 2, 3, 4, 5), 2)
+            test_concurrent_iteration(iterator, number_of_threads)
+
+    @threading_helper.reap_threads
+    def test_product(self):
+        number_of_threads = 10
+        number_of_iterations = 24
+
+        for it in range(number_of_iterations):
+            iterator = product((1, 2, 3, 4, 5), (10, 20, 30))
+            test_concurrent_iteration(iterator, number_of_threads)
+
+
+if __name__ == "__main__":
+    unittest.main()