python · prince8273 · May 19, 2026 · May 19, 2026
@@ -1517,3 +1517,12 @@ Task object
       used by end-user code.  See :meth:`uncancel` for more details.
 
       .. versionadded:: 3.11
+
+   .. method:: cancelling_since()
+
+      Return the event loop time at which :meth:`cancel` was first called, or
+      ``None`` if cancellation has not been requested.
+
+      Repeated calls to :meth:`cancel` do not change the recorded time.
+
+      .. versionadded:: 3.16
@@ -98,6 +98,7 @@ def __init__(self, coro, *, loop=None, name=None, context=None,
             self._name = str(name)
 
         self._num_cancels_requested = 0
+        self._cancel_requested_at = None
         self._must_cancel = False
         self._fut_waiter = None
         self._coro = coro
@@ -206,6 +207,8 @@ def cancel(self, msg=None):
         if self.done():
             return False
         self._num_cancels_requested += 1
+        if self._num_cancels_requested == 1:
+            self._cancel_requested_at = self._loop.time()
         # These two lines are controversial.  See discussion starting at
         # https://github.com/python/cpython/pull/31394#issuecomment-1053545331
         # Also remember that this is duplicated in _asynciomodule.c.
@@ -230,6 +233,9 @@ def cancelling(self):
         """
         return self._num_cancels_requested
 
+    def cancelling_since(self):
+        return self._cancel_requested_at
+
     def uncancel(self):
         """Decrement the task's count of cancellation requests.
 

@@ -539,6 +539,56 @@ async def task():
         finally:
             loop.close()
 
+    def test_cancelling_since_none_before_cancel(self):
+        loop = asyncio.new_event_loop()
+
+        async def task():
+            await asyncio.sleep(10)
+
+        try:
+            t = self.new_task(loop, task())
+            self.assertIsNone(t.cancelling_since())
+            t.cancel()
+            with self.assertRaises(asyncio.CancelledError):
+                loop.run_until_complete(t)
+        finally:
+            loop.close()
+
+    def test_cancelling_since_is_float_after_cancel(self):
+        loop = asyncio.new_event_loop()
+
+        async def task():
+            await asyncio.sleep(10)
+
+        try:
+            t = self.new_task(loop, task())
+            t.cancel()
+            ts = t.cancelling_since()
+            self.assertIsInstance(ts, float)
+            self.assertGreater(ts, 0)
+            with self.assertRaises(asyncio.CancelledError):
+                loop.run_until_complete(t)
+        finally:
+            loop.close()
+
+    def test_cancelling_since_stable_across_multiple_cancels(self):
+        loop = asyncio.new_event_loop()
+
+        async def task():
+            await asyncio.sleep(10)
+
+        try:
+            t = self.new_task(loop, task())
+            t.cancel()
+            first = t.cancelling_since()
+            t.cancel()
+            t.cancel()
+            self.assertEqual(t.cancelling_since(), first)
+            with self.assertRaises(asyncio.CancelledError):
+                loop.run_until_complete(t)
+        finally:
+            loop.close()
+
     def test_uncancel_basic(self):
         loop = asyncio.new_event_loop()
 

diff --git a/Misc/NEWS.d/next/Library/2026-05-19-12-20-00.gh-issue-150060.Gm2kQn.rst b/Misc/NEWS.d/next/Library/2026-05-19-12-20-00.gh-issue-150060.Gm2kQn.rst
@@ -0,0 +1,2 @@
+Add :meth:`asyncio.Task.cancelling_since` to report when cancellation was
+first requested for a task.
@@ -62,6 +62,7 @@ typedef struct TaskObj {
     unsigned task_must_cancel: 1;
     unsigned task_log_destroy_pending: 1;
     int task_num_cancels_requested;
+    PyObject *task_cancel_requested_at;  /* loop time of first cancel(), or Py_None */
     PyObject *task_fut_waiter;
     PyObject *task_coro;
     PyObject *task_name;
@@ -2342,6 +2343,7 @@ _asyncio_Task___init___impl(TaskObj *self, PyObject *coro, PyObject *loop,
     self->task_must_cancel = 0;
     self->task_log_destroy_pending = 1;
     self->task_num_cancels_requested = 0;
+    self->task_cancel_requested_at = Py_NewRef(Py_None);
     set_task_coro(self, coro);
 
     if (name == Py_None) {
@@ -2399,6 +2401,7 @@ TaskObj_clear(PyObject *op)
     clear_task_coro(task);
     Py_CLEAR(task->task_context);
     Py_CLEAR(task->task_name);
+    Py_CLEAR(task->task_cancel_requested_at);
     Py_CLEAR(task->task_fut_waiter);
     return 0;
 }
@@ -2411,6 +2414,7 @@ TaskObj_traverse(PyObject *op, visitproc visit, void *arg)
     Py_VISIT(task->task_context);
     Py_VISIT(task->task_coro);
     Py_VISIT(task->task_name);
+    Py_VISIT(task->task_cancel_requested_at);
     Py_VISIT(task->task_fut_waiter);
     FutureObj *fut = (FutureObj *)task;
     Py_VISIT(fut->fut_loop);
@@ -2588,6 +2592,15 @@ _asyncio_Task_cancel_impl(TaskObj *self, PyObject *msg)
 
     self->task_num_cancels_requested += 1;
 
+    if (self->task_num_cancels_requested == 1) {
+        PyObject *t = PyObject_CallMethodNoArgs(
+            ((FutureObj *)self)->fut_loop, &_Py_ID(time));
+        if (t == NULL) {
+            return NULL;
+        }
+        Py_SETREF(self->task_cancel_requested_at, t);
+    }
+
     // These three lines are controversial.  See discussion starting at
     // https://github.com/python/cpython/pull/31394#issuecomment-1053545331
     // and corresponding code in tasks.py.
@@ -2640,6 +2653,20 @@ _asyncio_Task_cancelling_impl(TaskObj *self)
     return PyLong_FromLong(self->task_num_cancels_requested);
 }
 
+/*[clinic input]
+@critical_section
+_asyncio.Task.cancelling_since
+
+Return the loop time when cancel() was first called, or None.
+[clinic start generated code]*/
+
+static PyObject *
+_asyncio_Task_cancelling_since_impl(TaskObj *self)
+/*[clinic end generated code: output=2670bb55581ab10e input=1f81f0a3b6e3da63]*/
+{
+    return Py_NewRef(self->task_cancel_requested_at);
+}
+
 /*[clinic input]
 @critical_section
 _asyncio.Task.uncancel
@@ -2918,6 +2945,7 @@ static PyMethodDef TaskType_methods[] = {
     _ASYNCIO_TASK_SET_EXCEPTION_METHODDEF
     _ASYNCIO_TASK_CANCEL_METHODDEF
     _ASYNCIO_TASK_CANCELLING_METHODDEF
+    _ASYNCIO_TASK_CANCELLING_SINCE_METHODDEF
     _ASYNCIO_TASK_UNCANCEL_METHODDEF
     _ASYNCIO_TASK_GET_STACK_METHODDEF
     _ASYNCIO_TASK_PRINT_STACK_METHODDEF

diff --git a/Modules/clinic/_asynciomodule.c.h b/Modules/clinic/_asynciomodule.c.h
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Add :meth:`asyncio.Task.cancelling_since` to report when cancellation was
		first requested for a task.