pid
===
.. image:: https://travis-ci.org/trbs/pid.svg?branch=master
:target: https://travis-ci.org/trbs/pid
.. image:: https://coveralls.io/repos/trbs/pid/badge.png
:target: https://coveralls.io/r/trbs/pid
.. image:: https://img.shields.io/pypi/v/pid.svg
:target: https://pypi.python.org/pypi/pid/
:alt: Latest PyPI version
.. image:: https://img.shields.io/pypi/dm/pid.svg
:target: https://pypi.python.org/pypi/pid/
:alt: Number of PyPI downloads
PidFile class featuring:
- stale detection
- pidfile locking (fcntl)
- chmod (default is 0o644)
- chown
- custom exceptions
Context Manager, Daemons and Logging
------------------------------------
PidFile can be used as a context manager::
from pid import PidFile
import os
with PidFile('foo') as p:
print(p.pidname) # -> 'foo'
print(p.piddir) # -> '/var/run' But you can modify it when initialize PidFile.
print(os.listdir('/var/run')) # -> ['foo.pid']
# pid file will delete after 'with' literal.
|
Logging to file is also possible when using PidFile with a daemon context manager
(e.g. `python-daemon <https://pypi.python.org/pypi/python-daemon/>`_). This requires some care in
handling the open files when the daemon starts to avoid closing them, which causes problems with the
logging. In particular, the open handlers should be preserved::
import sys
import logging
import logging.config
import daemon
from pid impor PidFile
logging.config.fileConfig(fname="logging.conf", disable_existing_loggers=False)
log = logging.getLogger(__name__)
PIDNAME = "/tmp/mydaemon.pid"
def get_logging_handles(logger):
handles = []
for handler in logger.handlers:
handles.append(handler.stream.fileno())
if logger.parent:
handles += get_logging_handles(logger.parent)
return handles
def daemonize():
file_preserve = get_logging_handles(logging.root)
pid_file = PidFile(pidname=PIDNAME)
with daemon.DaemonContext(stdout=sys.stdout,
stderr=sys.stderr,
stdin=sys.stdin,
pidfile=_pid_file,
files_preserve=files_preserve):
run_daemon_job()
print("DONE!")
if __name__ == "__main__":
daemonize()
This assumes a `logging.conf` file has been created, see e.g. `basic tutorial
<https://docs.python.org/3/howto/logging.html#logging-basic-tutorial>`_ for logging.
Decorator
---------
PidFile can also be used a a decorator::
from pid.decorator import pidfile
@pidfile()
def main():
pass
if __name__ == "__main__":
main()
Exception Order
---------------
In default mode PidFile will try to acquire a file lock before anything else.
This means that normally you get a PidFileAlreadyLockedError instead of the
PidFileAlreadyRunningError when running a program twice.
If you just want to know if a program is already running its easiest to catch
just PidFileError since it will capture all possible PidFile exceptions.
Behaviour
---------
Changes in version 2.0.0 and going forward:
* pid is now friendly with daemon context managers such as
`python-daemon <https://pypi.python.org/pypi/python-daemon/>`_ where
the PidFile context manager is passed as a parameter. The
new corrected behaviour will ensure the process environment is
determined at the time of acquiring/checking the lock. Prior
behaviour would determine the process environment when
instancing the class which may result in incorrect determination
of the PID in the case of a process forking after instancing
PidFile.
\
* Cleanup of pidfile on termination is done using `atexit` module.
The default SIGTERM handler doesn't cleanly exit and therefore
the atexit registered functions will not execute. A custom
handler which triggers the atexit registered functions for cleanup
will override the default SIGTERM handler. If a prior signal handler
has been configured, then it will not be overridden.
Raw data
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"description": "pid\n===\n\n.. image:: https://travis-ci.org/trbs/pid.svg?branch=master\n :target: https://travis-ci.org/trbs/pid\n\n.. image:: https://coveralls.io/repos/trbs/pid/badge.png\n :target: https://coveralls.io/r/trbs/pid\n\n.. image:: https://img.shields.io/pypi/v/pid.svg\n :target: https://pypi.python.org/pypi/pid/\n :alt: Latest PyPI version\n\n.. image:: https://img.shields.io/pypi/dm/pid.svg\n :target: https://pypi.python.org/pypi/pid/\n :alt: Number of PyPI downloads\n\nPidFile class featuring:\n\n - stale detection\n - pidfile locking (fcntl)\n - chmod (default is 0o644)\n - chown\n - custom exceptions\n\nContext Manager, Daemons and Logging\n------------------------------------\n\nPidFile can be used as a context manager::\n\n from pid import PidFile\n import os\n\n with PidFile('foo') as p:\n print(p.pidname) # -> 'foo'\n print(p.piddir) # -> '/var/run' But you can modify it when initialize PidFile.\n print(os.listdir('/var/run')) # -> ['foo.pid']\n\n # pid file will delete after 'with' literal.\n\n|\n\nLogging to file is also possible when using PidFile with a daemon context manager\n(e.g. `python-daemon <https://pypi.python.org/pypi/python-daemon/>`_). This requires some care in\nhandling the open files when the daemon starts to avoid closing them, which causes problems with the\nlogging. In particular, the open handlers should be preserved::\n\n import sys\n import logging\n import logging.config\n\n import daemon\n from pid impor PidFile\n\n logging.config.fileConfig(fname=\"logging.conf\", disable_existing_loggers=False)\n log = logging.getLogger(__name__)\n\n PIDNAME = \"/tmp/mydaemon.pid\"\n\n def get_logging_handles(logger):\n handles = []\n for handler in logger.handlers:\n handles.append(handler.stream.fileno())\n if logger.parent:\n handles += get_logging_handles(logger.parent)\n return handles\n\n def daemonize():\n file_preserve = get_logging_handles(logging.root)\n pid_file = PidFile(pidname=PIDNAME)\n\n with daemon.DaemonContext(stdout=sys.stdout,\n stderr=sys.stderr,\n stdin=sys.stdin,\n pidfile=_pid_file,\n files_preserve=files_preserve):\n\n run_daemon_job()\n print(\"DONE!\")\n\n if __name__ == \"__main__\":\n daemonize()\n\nThis assumes a `logging.conf` file has been created, see e.g. `basic tutorial\n<https://docs.python.org/3/howto/logging.html#logging-basic-tutorial>`_ for logging.\n\n\nDecorator\n---------\n\nPidFile can also be used a a decorator::\n\n from pid.decorator import pidfile\n\n @pidfile()\n def main():\n pass\n\n if __name__ == \"__main__\":\n main()\n\n\nException Order\n---------------\n\nIn default mode PidFile will try to acquire a file lock before anything else.\nThis means that normally you get a PidFileAlreadyLockedError instead of the\nPidFileAlreadyRunningError when running a program twice.\n\nIf you just want to know if a program is already running its easiest to catch\njust PidFileError since it will capture all possible PidFile exceptions.\n\nBehaviour\n---------\n\nChanges in version 2.0.0 and going forward:\n\n* pid is now friendly with daemon context managers such as\n `python-daemon <https://pypi.python.org/pypi/python-daemon/>`_ where\n the PidFile context manager is passed as a parameter. The\n new corrected behaviour will ensure the process environment is\n determined at the time of acquiring/checking the lock. Prior\n behaviour would determine the process environment when\n instancing the class which may result in incorrect determination\n of the PID in the case of a process forking after instancing\n PidFile.\n\n\\\n\n* Cleanup of pidfile on termination is done using `atexit` module.\n The default SIGTERM handler doesn't cleanly exit and therefore\n the atexit registered functions will not execute. A custom\n handler which triggers the atexit registered functions for cleanup\n will override the default SIGTERM handler. If a prior signal handler\n has been configured, then it will not be overridden.\n\n\n",
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