gh-103793: Defer formatting task name

Doc/whatsnew/3.12.rst

@@ -553,6 +553,9 @@ 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
 ========================

Lib/asyncio/tasks.py

@@ -104,7 +104,8 @@ def __init__(self, coro, *, loop=None, name=None, context=None):
             raise TypeError(f"a coroutine was expected, got {coro!r}")
 
         if name is None:
-            self._name = f'Task-{_task_name_counter()}'
+            # optimization: defer task name formatting to first get_name
+            self._name = None
         else:
             self._name = str(name)
 
@@ -143,6 +144,8 @@ def get_context(self):
         return self._context
 
     def get_name(self):
+        if self._name is None:
+            self._name = f'Task-{_task_name_counter()}'
         return self._name
 
     def set_name(self, value):

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.

Modules/_asynciomodule.c

@@ -2069,8 +2069,9 @@ _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
+        // set task_name to None to indicate deferred formatting
+        Py_INCREF(name);
     } else if (!PyUnicode_CheckExact(name)) {
         name = PyObject_Str(name);
     } else {
@@ -2449,6 +2450,12 @@ _asyncio_Task_get_name_impl(TaskObj *self)
 /*[clinic end generated code: output=0ecf1570c3b37a8f input=a4a6595d12f4f0f8]*/
 {
     if (self->task_name) {
+        if (Py_IsNone(self->task_name)) {
+            asyncio_state *state = get_asyncio_state_by_def((PyObject *)self);
+            PyObject *name = PyUnicode_FromFormat(
+                "Task-%" PRIu64, ++state->task_name_counter);
+            Py_XSETREF(self->task_name, name);
+        }
         return Py_NewRef(self->task_name);
     }