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Update debug mode docs.

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Ben Darnell 2013-04-08 22:46:30 -04:00
parent 5b3e9ec4a3
commit f229efbf06
1 changed files with 24 additions and 10 deletions
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docs/overview.rst
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@ -971,26 +971,40 @@ Debug mode and automatic reloading
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If you pass ``debug=True`` to the ``Application`` constructor, the app
will be run in debug mode. In this mode, templates will not be cached
and the app will watch for changes to its source files and reload itself
when anything changes. This reduces the need to manually restart the
server during development. However, certain failures (such as syntax
errors at import time) can still take the server down in a way that
debug mode cannot currently recover from.
will be run in debug/development mode. In this mode, several features
intended for convenience while developing will be enabled:
* The app will watch for changes to its source files and reload itself
when anything changes. This reduces the need to manually restart the
server during development. However, certain failures (such as syntax
errors at import time) can still take the server down in a way that
debug mode cannot currently recover from.
* Templates will not be cached, nor will static file hashes (used by the
``static_url`` function)
* When an exception in a ``RequestHandler`` is not caught, an error
page including a stack trace will be generated.
Debug mode is not compatible with ``HTTPServer``'s multi-process mode.
You must not give ``HTTPServer.start`` an argument greater than 1 if you
are using debug mode.
You must not give ``HTTPServer.start`` an argument other than 1 (or
call `tornado.process.fork_processes`) if you are using debug mode.
The automatic reloading feature of debug mode is available as a
standalone module in ``tornado.autoreload``, and is optionally used by
the test runner in ``tornado.testing.main``.
standalone module in ``tornado.autoreload``. The two can be used in
combination to provide extra robustness against syntax errors: set
``debug=True`` within the app to detect changes while it is running,
and start it with ``python -m tornado.autoreload myserver.py`` to catch
any syntax errors or other errors at startup.
Reloading loses any Python interpreter command-line arguments (e.g. ``-u``)
because it re-executes Python using ``sys.executable`` and ``sys.argv``.
Additionally, modifying these variables will cause reloading to behave
incorrectly.
On some platforms (including Windows and Mac OSX prior to 10.6), the
process cannot be updated "in-place", so when a code change is
detected the old server exits and a new one starts. This has been
known to confuse some IDEs.
Running Tornado in production
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~