diff --git a/Doc/howto/logging-cookbook.rst b/Doc/howto/logging-cookbook.rst index 16df3b730ac80e..5b079744df12ed 100644 --- a/Doc/howto/logging-cookbook.rst +++ b/Doc/howto/logging-cookbook.rst @@ -397,6 +397,14 @@ which, when run, will produce: MainThread: Look out! +.. note:: Although the earlier discussion wasn't specifically talking about + async code, but rather about slow logging handlers, it should be noted that + when logging from async code, network and even file handlers could lead to + problems (blocking the event loop) because some logging is done from + :mod:`asyncio` internals. It might be best, if any async code is used in an + application, to use the above approach for logging, so that any blocking code + runs only in the ``QueueListener`` thread. + .. versionchanged:: 3.5 Prior to Python 3.5, the :class:`QueueListener` always passed every message received from the queue to every handler it was initialized with. (This was