Add additional unit tests for free-threading.

Author: nascheme

Lib/test/test_free_threading/test_races.py

@@ -0,0 +1,131 @@
+# It's most useful to run these tests with ThreadSanitizer enabled.
+import sys
+import functools
+import threading
+import time
+import unittest
+
+from test.support import threading_helper
+
+
+class TestBase(unittest.TestCase):
+    pass
+
+
+def do_race(func1, func2):
+    """Run func1() and func2() repeatedly in separate threads."""
+    n = 1000
+
+    def repeat(func):
+        for _i in range(n):
+            func()
+
+    threads = [
+        threading.Thread(target=functools.partial(repeat, func1)),
+        threading.Thread(target=functools.partial(repeat, func2)),
+    ]
+    for thread in threads:
+        thread.start()
+    for thread in threads:
+        thread.join()
+
+
+@threading_helper.requires_working_threading()
+class TestRaces(TestBase):
+    def test_racing_cell_set(self):
+        """Test cell object gettr/settr properties."""
+
+        def nested_func():
+            x = 0
+
+            def inner():
+                nonlocal x
+                x += 1
+
+        # This doesn't race because LOAD_DEREF and STORE_DEREF on the
+        # cell object use critical sections.
+        do_race(nested_func, nested_func)
+
+        def nested_func2():
+            x = 0
+
+            def inner():
+                y = x
+                frame = sys._getframe(1)
+                frame.f_locals["x"] = 2
+
+            return inner
+
+        def mutate_func2():
+            inner = nested_func2()
+            cell = inner.__closure__[0]
+            old_value = cell.cell_contents
+            cell.cell_contents = 1000
+            time.sleep(0)
+            cell.cell_contents = old_value
+            time.sleep(0)
+
+        # This revealed a race with cell_set_contents() since it was missing
+        # the critical section.
+        do_race(nested_func2, mutate_func2)
+
+    def test_racing_cell_cmp_repr(self):
+        """Test cell object compare and repr methods."""
+
+        def nested_func():
+            x = 0
+            y = 0
+
+            def inner():
+                return x + y
+
+            return inner.__closure__
+
+        cell_a, cell_b = nested_func()
+
+        def mutate():
+            cell_a.cell_contents += 1
+
+        def access():
+            cell_a == cell_b
+            s = repr(cell_a)
+
+        # cell_richcompare() and cell_repr used to have data races
+        do_race(mutate, access)
+
+    def test_racing_load_super_attr(self):
+        """Test (un)specialization of LOAD_SUPER_ATTR opcode."""
+
+        class C:
+            def __init__(self):
+                try:
+                    super().__init__
+                    super().__init__()
+                except RuntimeError:
+                    pass  #  happens if __class__ is replaced with non-type
+
+        def access():
+            C()
+
+        def mutate():
+            # Swap out the super() global with a different one
+            real_super = super
+            globals()["super"] = lambda s=1: s
+            time.sleep(0)
+            globals()["super"] = real_super
+            time.sleep(0)
+            # Swap out the __class__ closure value with a non-type
+            cell = C.__init__.__closure__[0]
+            real_class = cell.cell_contents
+            cell.cell_contents = 99
+            time.sleep(0)
+            cell.cell_contents = real_class
+
+        # The initial PR adding specialized opcodes for LOAD_SUPER_ATTR
+        # had some races (one with the super() global changing and one
+        # with the cell binding being changed).
+        do_race(access, mutate)
+
+
+if __name__ == "__main__":
+    unittest.main()