deprecate got_first_request property

CHANGES.rst

@@ -23,6 +23,7 @@ Unreleased
 
 -   Importing ``escape`` and ``Markup`` from ``flask`` is deprecated. Import them
     directly from ``markupsafe`` instead. :pr:`4996`
+-   The ``app.got_first_request`` property is deprecated. :pr:`4997`
 -   Use modern packaging metadata with ``pyproject.toml`` instead of ``setup.cfg``.
     :pr:`4947`
 -   Ensure subdomains are applied with nested blueprints. :issue:`4834`

src/flask/app.py

@@ -8,7 +8,6 @@ import weakref
 from collections.abc import Iterator as _abc_Iterator
 from datetime import timedelta
 from itertools import chain
-from threading import Lock
 from types import TracebackType
 
 import click
@@ -496,7 +495,6 @@ class Flask(Scaffold):
         # tracks internally if the application already handled at least one
         # request.
         self._got_first_request = False
-        self._before_request_lock = Lock()
 
         # Add a static route using the provided static_url_path, static_host,
         # and static_folder if there is a configured static_folder.
@@ -592,8 +590,18 @@ class Flask(Scaffold):
         """This attribute is set to ``True`` if the application started
         handling the first request.
 
+        .. deprecated:: 2.3
+            Will be removed in Flask 2.4.
+
         .. versionadded:: 0.8
         """
+        import warnings
+
+        warnings.warn(
+            "'got_first_request' is deprecated and will be removed in Flask 2.4.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
         return self._got_first_request
 
     def make_config(self, instance_relative: bool = False) -> Config:

tests/test_basic.py

@@ -1657,7 +1657,6 @@ def test_no_setup_after_first_request(app, client):
     def index():
         return "Awesome"
 
-    assert not app.got_first_request
     assert client.get("/").data == b"Awesome"
 
     with pytest.raises(AssertionError) as exc_info: