django-graceful-session-cleanup

Warning: currently only works with mysql

A simple management command that can delete expired sessions from large session tables without killing the site.

The main use case is if you have a live application with millions of stale sessions in the database. Runnung the regular python manage.py cleanup will potentially lock your database for hours, essentially killing your site.

With django-graceful-session-cleanup you can gradually delete all the sessions.

To achieve this it will always only delete a small amount of the expired sessions per query and then sleep for a few seconds. There are commandline options to control interval, sleep time and amount of sessions to delete per interval.

Installation

install the package:

pip install django-graceful-session-cleanup

add it to INSTALLED_APPS:

INSTALLED_APPS = [
    ....
    'graceful_session_cleanup',
]

run the management command:

python manage.py graceful_session_cleanup

There are a few options you can use:

python manage.py graceful_session_cleanup --sleep-seconds 9 --delete-count 1000 --iteration-count 200

This will delete 1000 expired session entries, wait for 5 seconds so other processes can use the database and then repeat this 200 times. Depending on database load (assuming deleting takes 1s) this will take (9s + 1s) * 200 = 2000s.

there is help on the commandline:

$ python manage.py help graceful_session_cleanup
Usage: django graceful_session_cleanup [options]

Can be run as a cronjob or directly to clean out old data from the database (only expired sessions at the moment). Does this in a live db friendly way by never hogging the connection too long.

Options:
  -v VERBOSITY, --verbosity=VERBOSITY
                        Verbosity level; 0=minimal output, 1=normal output,
                        2=all output
  --settings=SETTINGS   The Python path to a settings module, e.g.
                        "myproject.settings.main". If this isn't provided, the
                        DJANGO_SETTINGS_MODULE environment variable will be
                        used.
  --pythonpath=PYTHONPATH
                        A directory to add to the Python path, e.g.
                        "/home/djangoprojects/myproject".
  --traceback           Print traceback on exception
  -s SLEEP_SECONDS, --sleep-seconds=SLEEP_SECONDS
                        How long to sleep between each delete operation.
  -c DELETE_COUNT, --delete-count=DELETE_COUNT
                        How many expired sessions to delete per iteration.
  -i ITERATION_COUNT, --iteration-count=ITERATION_COUNT
                        How many iterations to run.
  --version             show program's version number and exit
  -h, --help            show this help message and exit