[PR #8267/509fb269 backport][3.9] Add note about tasks that should be…

… cancelled on shutdown (#8268) **This is a backport of PR #8267 as merged into master (509fb26).** Co-authored-by: Sam Bull <[email protected]>
aio-libs · Mar 30, 2024 · 3a13bd5 · 3a13bd5
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diff --git a/CHANGES/8267.doc.rst b/CHANGES/8267.doc.rst
@@ -0,0 +1 @@
+Added a note about canceling tasks to avoid delaying server shutdown -- by :user:`Dreamsorcerer`.
diff --git a/docs/web_advanced.rst b/docs/web_advanced.rst
@@ -952,6 +952,14 @@ steps 4 and 7).
    :ref:`cleanup contexts<aiohttp-web-cleanup-ctx>`.
 7. Cancel any remaining tasks and wait on them to complete.
 
+.. note::
+
+   When creating new tasks in a handler which _should_ be cancelled on server shutdown,
+   then it is important to keep track of those tasks and explicitly cancel them in a
+   :attr:`Application.on_shutdown` callback. As we can see from the above steps,
+   without this the server will wait on those new tasks to complete before it continues
+   with server shutdown.
+
 Websocket shutdown
 ^^^^^^^^^^^^^^^^^^