6 Python 2 and Python 3 applications using the standard
7 <a href="https://docs.python.org/3/howto/logging.html" class="ext"><code>logging</code> module</a>
8 can be traced by LTTng using the LTTng-UST Python agent.
10 Import the `lttngust` package in your Python application. For example:
18 logger = logging.getLogger('my-logger')
21 logger.debug('debug message')
22 logger.info('info message')
23 logger.warn('warn message')
24 logger.error('error message')
25 logger.critical('critical message')
29 if __name__ == '__main__':
33 Importing `lttngust` adds a logging handler which emits LTTng-UST
34 events. You do not need to get a special logger for tracing to work.
36 Use the `--python` option of the `lttng enable-event`,
37 `lttng disable-event`, and `lttng list` commands to target
38 Python applications. For example, here's how to enable the events
39 produced by the Python logger above:
42 lttng enable-event --python my-logger
45 Standard Python log levels are supported using the `PYTHON_` prefix.
46 For example, here's how to enable the warning (and more important)
47 events produced by the Python logger above:
50 lttng enable-event --python my-logger --loglevel PYTHON_WARNING
53 See [Enabling and disabling events](#doc-enabling-disabling-events) for
56 When loading, the LTTng-UST Python agent tries to register to the
57 [session daemon](#doc-lttng-sessiond). Note that the session daemon
58 needs to be started _before_ the Python application is started. If a
59 session daemon is found, the agent tries to register to it during
60 5 seconds, after which the application continues without LTTng
61 tracing support. This timeout value is overriden by the
62 `LTTNG_UST_PYTHON_REGISTER_TIMEOUT` environment variable (milliseconds).
64 If the session daemon stops while a registered Python application is
65 registered, the application retries to connect and register to a session
66 daemon every 3 seconds. This timeout value is overridden by the
67 `LTTNG_UST_PYTHON_REGISTER_RETRY_DELAY` environment variable.