Cron¶

Basics¶

Cron is a tool to run background jobs and is essential for the production environment. Periodically executed Cron modules recalculate visibility, generate XML feeds and sitemaps, provide error reporting, etc.

By default, you can configure your own cron configurations in app/config/cron.yaml file.

Cron modules use standard crontab expressions (5 fields: minute, hour, day of month, month, day of week) for scheduling. This means you can use all standard cron syntax features including ranges (1-5), lists (0,15,30), steps (*/10), and combinations thereof.

For example:

App\Cron\MyModule:
    tags:
        - { name: shopsys.cron, cron: '*/15 * * * *', instanceName: default, readableName: 'My task' }

This would run the module every 15 minutes. See crontab syntax for the full expression reference.

If you want to show Cron overview table for non-superadmin users you need add parameter shopsys.display_cron_overview_for_superadmin_only set to false in your config/parameters.yaml:

Default Cron Commands¶

There is some prepared configuration in a file app/config/cron.yaml in project-base.

Running Cron Jobs¶

Do not forget to set up a cron on your server to execute php phing cron every 5 minutes.

Multiple Cron Instances¶

By default, all cron jobs are run as part of one, default, instance. However, you may want to have several instances to be able to run, for example, lots of transfers from/into ERP systems and these transfers could block other cron processes. Separating the cron jobs into two (or more) cron instances allows you to run some jobs in parallel.

The instance of cron is actually a named group of cron jobs.

You can learn how to set up multiple cron instances in Working with Multiple Cron Instances cookbook.

Cron Limitations¶

One cron run can only be run for a limited time by default to prevent high-memory usage of long-running jobs in PHP. You can configure the behaviour of each instance in app/config/cron.yaml:

parameters:
    cron_instances:
        default:
            run_every_min: 5
            timeout_iterated_cron_sec: 240
            stop_on_failure: true

That means, if the time needed to run all planned cron modules is higher than 240 seconds, not all cron modules will be run in a current iteration. That's usually not a problem as long-running cron modules are not executed every iteration set in run_every_min with default to 5 minutes, but in some cases, the overall time of the "every 5 minutes" cron modules can be higher (for example, considerable amount of products to export to Elasticsearch). Then it's possible, some cron modules will never be run.

It's crucial to monitor your crons and, if necessary, update their periodicity and timeout or split them into multiple Cron Instances.

The stop_on_failure option controls whether the instance stops executing subsequent cron modules when one module fails. It defaults to true. Set it to false for instances whose modules are independent of each other so that a failure in one module does not prevent the remaining modules from running.