python · gvanrossum · Apr 29, 2023 · Apr 24, 2023 · Apr 24, 2023 · Apr 24, 2023
diff --git a/Doc/whatsnew/3.12.rst b/Doc/whatsnew/3.12.rst
@@ -565,6 +565,9 @@ Optimizations
  replacement strings containing group references by 2--3 times.
  (Contributed by Serhiy Storchaka in :gh:`91524`.)

+* Speed up :class:`asyncio.Task` creation by deferring expensive string formatting.
+  (Contributed by Itamar O in :gh:`103793`.)
+

 CPython bytecode changes
 ========================

@@ -399,6 +399,18 @@ async def notmuch():
        self.loop.run_until_complete(t1)
        self.loop.run_until_complete(t2)

+    def test_task_set_name_pylong(self):
+        # test that setting the task name to a PyLong explicitly doesn't
+        # incorrectly trigger the deferred name formatting logic
+        async def notmuch():
+            return 123
+
+        t = self.new_task(self.loop, notmuch(), name=987654321)
+        self.assertEqual(t.get_name(), '987654321')
+        t.set_name(123456789)
+        self.assertEqual(t.get_name(), '123456789')
+        self.loop.run_until_complete(t)
+
    def test_task_repr_name_not_str(self):
        async def notmuch():
            return 123

diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-04-24-14-38-16.gh-issue-103793.kqoH6Q.rst b/Misc/NEWS.d/next/Core and Builtins/2023-04-24-14-38-16.gh-issue-103793.kqoH6Q.rst
@@ -0,0 +1,3 @@
+Optimized asyncio Task creation by deferring expensive string formatting
+(task name generation) from Task creation to the first time ``get_name`` is
+called. This makes asyncio benchmarks up to 5% faster.
@@ -2069,8 +2069,10 @@ _asyncio_Task___init___impl(TaskObj *self, PyObject *coro, PyObject *loop,
    Py_XSETREF(self->task_coro, coro);

    if (name == Py_None) {
-        name = PyUnicode_FromFormat("Task-%" PRIu64,
-                                    ++state->task_name_counter);
+        // optimization: defer task name formatting
+        // store the task counter as PyLong in the name
+        // for deferred formatting in get_name
+        name = PyLong_FromUnsignedLongLong(++state->task_name_counter);
    } else if (!PyUnicode_CheckExact(name)) {
        name = PyObject_Str(name);
    } else {
@@ -2449,6 +2451,13 @@ _asyncio_Task_get_name_impl(TaskObj *self)
 /*[clinic end generated code: output=0ecf1570c3b37a8f input=a4a6595d12f4f0f8]*/
 {
    if (self->task_name) {
+        if (PyLong_CheckExact(self->task_name)) {
+            PyObject *name = PyUnicode_FromFormat("Task-%S", self->task_name);
+            if (name == NULL) {
+                return NULL;
+            }
+            Py_SETREF(self->task_name, name);
+        }
        return Py_NewRef(self->task_name);
    }