python · colesbury · Nov 23, 2025 · Nov 23, 2025
diff --git a/Lib/test/test_free_threading/test_monitoring.py b/Lib/test/test_free_threading/test_monitoring.py
@@ -72,6 +72,9 @@ def test_instrumentation(self):
                break

            self.during_threads()
+            # Sleep to avoid setting monitoring events too rapidly and
+            # overflowing the global version counter
+            time.sleep(0.0001)

        self.after_test()


diff --git a/Misc/NEWS.d/next/Core and Builtins/2025-11-22-10-43-26.gh-issue-120158.41_rXd.rst b/Misc/NEWS.d/next/Core and Builtins/2025-11-22-10-43-26.gh-issue-120158.41_rXd.rst
@@ -0,0 +1,2 @@
+Fix inconsistent state when enabling or disabling monitoring events too many
+times.
diff --git a/Python/instrumentation.c b/Python/instrumentation.c
@@ -1989,12 +1989,12 @@ _PyMonitoring_SetEvents(int tool_id, _PyMonitoringEventSet events)
    if (existing_events == events) {
        return 0;
    }
-    set_events(&interp->monitors, tool_id, events);
    uint32_t new_version = global_version(interp) + MONITORING_VERSION_INCREMENT;
    if (new_version == 0) {
        PyErr_Format(PyExc_OverflowError, "events set too many times");
        return -1;
    }
+    set_events(&interp->monitors, tool_id, events);
    set_global_version(tstate, new_version);
 #ifdef _Py_TIER2
    _Py_Executors_InvalidateAll(interp, 1);
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Fix inconsistent state when enabling or disabling monitoring events too many
		times.