diff --git a/Doc/library/asyncio-dev.rst b/Doc/library/asyncio-dev.rst index ce1275b4e02..bf77a8fb794 100644 --- a/Doc/library/asyncio-dev.rst +++ b/Doc/library/asyncio-dev.rst @@ -14,16 +14,22 @@ This page lists common traps and explains how to avoid them. Debug mode of asyncio --------------------- -To enable the debug mode globally, set the environment variable -:envvar:`PYTHONASYNCIODEBUG` to ``1``. To see debug traces, set the log level -of the :ref:`asyncio logger ` to :py:data:`logging.DEBUG`. The -simplest configuration is:: +The implementation of :mod:`asyncio` module has been written for performances. +To development with asyncio, it's required to enable the debug checks to ease +the development of asynchronous code. - import logging - # ... - logging.basicConfig(level=logging.DEBUG) +Setup an application to enable all debug checks: -Examples of effects of the debug mode: +* Enable the asyncio debug mode globally by setting the environment variable + :envvar:`PYTHONASYNCIODEBUG` to ``1`` +* Set the log level of the :ref:`asyncio logger ` to + :py:data:`logging.DEBUG`. For example, call + ``logging.basicConfig(level=logging.DEBUG)`` at startup. +* Configure the :mod:`warnings` module to display :exc:`ResourceWarning` + warnings. For example, use the ``-Wdefault`` command line option of Python to + display them. + +Examples debug checks: * Log :ref:`coroutines defined but never "yielded from" ` @@ -33,6 +39,8 @@ Examples of effects of the debug mode: * Log callbacks taking more than 100 ms to be executed. The :attr:`BaseEventLoop.slow_callback_duration` attribute is the minimum duration in seconds of "slow" callbacks. +* :exc:`ResourceWarning` warnings are emitted when transports and event loops + are :ref:`not closed explicitly `. .. seealso:: @@ -372,14 +380,15 @@ traceback where the task was created. Example of log in debug mode:: :ref:`Detect coroutine objects never scheduled `. +.. _asyncio-close-transports: -Close transports ----------------- +Close transports and event loops +-------------------------------- When a transport is no more needed, call its ``close()`` method to release -resources. +resources. Event loops must also be closed explicitly. -If a transport (or an event loop) is not closed explicitly, a -:exc:`ResourceWarning` warning will be emitted in its destructor. The -:exc:`ResourceWarning` warnings are hidden by default: use the ``-Wd`` command -line option of Python to show them. +If a transport or an event loop is not closed explicitly, a +:exc:`ResourceWarning` warning will be emitted in its destructor. By default, +:exc:`ResourceWarning` warnings are ignored. The :ref:`Debug mode of asyncio +` section explains how to display them.