Admin Interface#

autocron comes with a command line tool to inspect the content of the database and to manage the settings:

$ autocron
usage: autocron command line tool [-h] [-i] [--reset-defaults]
[--delete-database] [--set-max-workers MAX_WORKERS]
[--set-worker-idle-time WORKER_IDLE_TIME]
[--set-monitor-idle-time MONITOR_IDLE_TIME]
[--set-monitor-lock MONITOR_LOCK]
[--set-autocron-lock AUTOCRON_LOCK]
[--set-result-ttl RESULT_TTL] [-t] [-d] [-c] [-r] database
database:

Name of the database to work on, required.

-c, --get-cron-tasks:

list all registered task which are cronjobs.

-d, --get-tasks-on-due:

list all waiting tasks that are on due.

--delete-database:

deletes the selected database.

-h:

show the help menu

-i:

views the current the settings, number of aktive workers and their corresponding pids in case autocron is running.

-r, --get-results:

list all available results.

--reset-defaults:

overwrite the settings in the database with the default values.

--set-autocron-lock:

set the lock flag of autocron. If the flag is set, autocron is disabled and will not start. This can be helpful on development or debugging when additional background-processes may be disturbing at best. Accepts the case-insensitive arguments on, off, true, false. on and true are setting the flag (disable autocron), off and false delete the flag (enable autocron):

--set-max-workers:

set number of maximum worker processes. Takes an integer as argument. (autocron will start exactly this number of workers and not “as up to”.) To take effect autocron needs to restart.

--set-monitor-idle-time:

set the idle time (in seconds) of the monitor thread supervising the workers. Default value is 5 seconds. Normalwise there will be no need to change this.

--set-monitor-lock:

set monitor lock flag. This is an internal flag indicating that a monitor process is active. When autocron starts with multiple processes of the web-application in parallel, the first process will start the monitor and the worker processes. Setting the flag prevents the other processes to do the same and start additonal workers on their own. On shutdown, this flag gets released. However the admin tool allows to set the flag if something does not work as it should. Arguments are on, off, true, false. During normal operation you should never have the need to deal with this setting.

--set-worker-idle-time:

set the idle time (in seconds) for the worker processes. If no tasks on due the worker(s) will sleep for the given time before checking again for new tasks. Defaults to 2 seconds. On busy sites this can be used for fine-tuning.

--set-result-ttl:

set the result time to life (ttl, in seconds). Stored results are deleted after this timespan. A change to take effect needs a restart of the application. The change will applied to new results. Already stored results keep the previous assigned ttl. Defauts to 1800 seconds (30 minutes).

-t, --get-tasks:

list all waiting tasks.

Settings#

autocron comes with default settings. The admin interface allows to change the settings. By default autocron starts with one (1) worker process. When no tasks are on due the worker sleeps for 2 seconds. When waking up the worker selects all tasks on due for processing. After handling these tasks the worker looks for new tasks that may have been registered meanwhile. If no tasks have been registered the worker goes into idle mode again. The duration of the idle-time can be modified with the option --set-worker-idle-time.

A second running worker may select tasks for processing that are registered during the time the first worker is busy. More than one workers make sense if tasks are registered in a faster pace than a single worker can process them. With the --set-max-workers option the number of workers can get set. To take effect, autocron needs a restart. As autocron gets started from the application the application has to restart. There is no upper limit for the number of workers, but it makes no sense to set the number too high (just to be on the “safe side”). As a rule of thumb the upper limit of workers should not be larger than the number of available cpu cores. Best advice is to check the server- and process-loads to find the best settings. The option -i lists the pids of the worker processes for inspection.

For debugging an application, active background processes can be disturbing. autocron can get deactivated with the --set-autocron-lock setting. The default value is False. Set the value to True or on to set the flag to deactivate autocron (the arguments are case insensitive). Even when autocron.start() is called in the code, autocron will check the flag and will not start. The delay decorator will behave the same returning a TaskResult instance but the task itself will get executed in sync, i.e. a blocking task will block for some time.

Database Storage#

All settings are stored in the autocron database. The default location for the databases is in the ~.autocron/ directory. When autocron starts and can not find its database, a new database gets created with the default settings. During start-up of the application autocron may already preregister decorated functions for later execution. The registration will be completed with the call of autocron.start(). On shutting down the application, all unhandled tasks keep persistent in the autocron database and will get handled the next time the application starts. If the database file gets deleted, the contents are lost (of course). Otherwise it is safe to delete the databases – next time when the application starts, autocron will create a fresh one.