gh-116738: Make bisect module thread-safe

Lib/test/test_free_threading/test_bisect.py

@@ -0,0 +1,43 @@
+import unittest
+
+from itertools import cycle
+
+from test.support import import_helper, threading_helper, subTests
+from test.support.threading_helper import run_concurrently
+
+bisect = import_helper.import_module("bisect")
+
+
+NTHREADS = 10
+
+
+@threading_helper.requires_working_threading()
+class TestBisect(unittest.TestCase):
+    @subTests("insort_func", [bisect.insort_left, bisect.insort_right])
+    def test_racing_insort(self, insort_func):
+        lst = list(range(10))
+        insort_items_iter = cycle(list(range(11)))
+
+        def worker(lst, insort_items_iter):
+            for _ in range(10):
+                insort_item = next(insort_items_iter)
+                insort_func(lst, insort_item)
+
+        run_concurrently(
+            worker_func=worker,
+            nthreads=NTHREADS,
+            args=(lst, insort_items_iter),
+        )
+
+        self.assertTrue(self.is_sorted_ascending(lst))
+
+    @staticmethod
+    def is_sorted_ascending(lst):
+        """
+        Check if the list is sorted in ascending order (non-decreasing).
+        """
+        return all(lst[i - 1] <= lst[i] for i in range(1, len(lst)))
+
+
+if __name__ == "__main__":
+    unittest.main()

Misc/NEWS.d/next/Core_and_Builtins/2025-07-22-11-09-16.gh-issue-116738.uAgWNZ.rst

@@ -0,0 +1,2 @@
+Make functions in :mod:`bisect` thread-safe on the :term:`free threaded
+<free threading>` build.

Modules/_bisectmodule.c

@@ -179,6 +179,7 @@ _bisect_bisect_right_impl(PyObject *module, PyObject *a, PyObject *x,
 }
 
 /*[clinic input]
+@critical_section a
 _bisect.insort_right
 
     a: object
@@ -201,7 +202,7 @@ A custom key function can be supplied to customize the sort order.
 static PyObject *
 _bisect_insort_right_impl(PyObject *module, PyObject *a, PyObject *x,
                           Py_ssize_t lo, Py_ssize_t hi, PyObject *key)
-/*[clinic end generated code: output=ac3bf26d07aedda2 input=f60777d2b6ddb239]*/
+/*[clinic end generated code: output=ac3bf26d07aedda2 input=93bd855be0c1add7]*/
 {
     PyObject *result, *key_x;
     Py_ssize_t index;
@@ -365,6 +366,7 @@ _bisect_bisect_left_impl(PyObject *module, PyObject *a, PyObject *x,
 
 
 /*[clinic input]
+@critical_section a
 _bisect.insort_left
 
     a: object
@@ -387,7 +389,7 @@ A custom key function can be supplied to customize the sort order.
 static PyObject *
 _bisect_insort_left_impl(PyObject *module, PyObject *a, PyObject *x,
                          Py_ssize_t lo, Py_ssize_t hi, PyObject *key)
-/*[clinic end generated code: output=b1d33e5e7ffff11e input=0a700a82edbd472c]*/
+/*[clinic end generated code: output=b1d33e5e7ffff11e input=93e06f5a323e09ef]*/
 {
     PyObject *result, *key_x;
     Py_ssize_t index;