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asyncio doc: explain how to display ResourceWarning in the debug mode section

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Victor Stinner 2015-02-04 16:14:33 +01:00
parent 2fc2313038
commit 6a1b004b83
1 changed files with 24 additions and 15 deletions
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39
Doc/library/asyncio-dev.rst
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@ -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 <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 <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"
<asyncio-coroutine-not-scheduled>`
@ -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 <asyncio-close-transports>`.
.. seealso::
@ -372,14 +380,15 @@ traceback where the task was created. Example of log in debug mode::
:ref:`Detect coroutine objects never scheduled <asyncio-coroutine-not-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
<asyncio-debug-mode>` section explains how to display them.