Customizing crons reference

This topic helps you set up crontabs and optionally cron groups for custom modules. If your custom module needs to schedule tasks periodically, you must set up a crontab for that module. A crontab is a cron job configuration.

Optionally, you can set up a custom group, which among other things enables you to run cron jobs defined in that group independently of other cron jobs.

For a step-by-step tutorial, see Configure custom cron jobs and cron groups (tutorial).

For an overview about cron jobs, see Configure cron jobs.

Configure cron groups

This section discusses how to optionally create a cron group for a custom module. If you do not need to do this, continue with the next section.

A cron group is a logical group that enables you to easily run cron for more than one process at a time. Most Commerce modules use the default cron group; some modules use the index group.

If you are implementing cron for a custom module, you can choose to use the default group or a different group.

To configure a cron group for your module:

Create a crontab.xml file in your module directory:

<your component base dir>/<vendorname>/module-<name>/etc/crontab.xml

For one group, the file should have the following contents:

<config>
    <group id="<group_name>">
        <job name="<job_name>" instance="<classpath>" method="<method>">
            <schedule><time></schedule>
        </job>
    </group>
</config>

Where:

Value Description
group_name Name of the cron group. The group name does not have to be unique. You can run cron for one group at a time.
job_name Unique ID for this cron job.
classpath Class to be instantiated (classpath).
method Method in classpath to call.
time Schedule in cron format. Omit this parameter if the schedule is defined in the Commerce database or other storage.

The resulting crontab.xml with two groups may look like this:

<config>
    <group id="default">
        <job name="<job_1_name>" instance="<classpath>" method="<method_name>">
            <schedule>* * * * *</schedule>
        </job>
        <job name="<job_2_name>" instance="<classpath>" method="<method_name>">
            <schedule>* * * * *</schedule>
        </job>
    </group>
    <group id="index">
        <job name="<job_3_name>" instance="<classpath>" method="<method_name>">
            <schedule>* * * * *</schedule>
        </job>
        <job name="<job_4_name>" instance="<classpath>" method="<method_name>">
            <schedule>* * * * *</schedule>
        </job>
    </group>
</config>

As an example, see Magento_Customer crontab.xml.

Specifying Cron group options

You may declare a new group and specify its configuration options (all of which run in store view scope) via the cron_groups.xml file, located in:

<your component base dir>/<vendorname>/module-<name>/etc/cron_groups.xml

Below is an example of the cron_groups.xml file:

<config>
    <group id="<group_name>">
        <schedule_generate_every>1</schedule_generate_every>
        <schedule_ahead_for>4</schedule_ahead_for>
        <schedule_lifetime>2</schedule_lifetime>
        <history_cleanup_every>10</history_cleanup_every>
        <history_success_lifetime>60</history_success_lifetime>
        <history_failure_lifetime>600</history_failure_lifetime>
        <use_separate_process>1</use_separate_process>
    </group>
</config>

Where:

Option Description
schedule_generate_every Frequency (in minutes) that schedules are written to the cron_schedule table.
schedule_ahead_for Time (in minutes) in advance that schedules are written to the cron_schedule table.
schedule_lifetime Window of time (in minutes) that a cron job must start or the cron job is considered missed (“too late” to run).
history_cleanup_every Time (in minutes) that cron history is kept in the database.
history_success_lifetime Time (in minutes) that the record of successfully completed cron jobs is kept in the database.
history_failure_lifetime Time (in minutes) that the record of failed cron jobs is kept in the database.
use_separate_process Run this cron group’s jobs in a separate php process

Disable a cron job

Cron jobs do not have a disable feature like we have for observers. However, a cron job can be disabled by using the following technique: schedule a time that contains a date which will never happen.

For example, disable the visitor_clean cron job which defined in Magento_Customer module:

...
<group id="default">
    <job name="visitor_clean" instance="Magento\Customer\Model\Visitor" method="clean">
        <schedule>0 0 * * *</schedule>
    </job>
</group>
...

To disable the visitor_clean cron job, create a custom module and rewrite the visitor_clean cron job schedule:

...
<group id="default">
    <job name="visitor_clean" instance="Magento\Customer\Model\Visitor" method="clean">
        <schedule>0 0 30 2 *</schedule>
    </job>
</group>
...

Now, the visitor_clean cron job has been set to run at 00:00 on the 30th of February - at the date which will never occur.

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