Magento already provides a suitable mechanism through the LockManagerInterface . Acquire a lock before starting the main operation. If the lock already exists, the second execution can exit immediately.

use Magento\Framework\Lock\LockManagerInterface;

class Import
{
    public function __construct(
        private LockManagerInterface $lockManager
    ) {
    }

    public function execute(): void
    {
        $lockName = 'vendor_module_import';

        if (!$this->lockManager->lock($lockName, 0)) {
            return;
        }

        try {
            // Run import
        } finally {
            $this->lockManager->unlock($lockName);
        }
    }
}

The lock name should uniquely identify the process. While vendor_module_import is locked, another run with the same lock cannot begin at the same time.

The important part is the finally: Even if the cron job throws an exception, the lock is released afterwards.

Magento uses its lock mechanism internally in several places. For longer-running custom cron jobs, LockManagerInterface is cleaner and safer than a homemade status file or a flag in the database.

Magento cron jobs are normally defined in a crontab.xml. A simple code search can reveal the corresponding definition.

grep -R --include="crontab.xml" 'job name="mein_job_code"' app/code vendor

If the job is called vendor_sync_products , search for its name.

grep -R --include="crontab.xml" 'job name="vendor_sync_products"' app/code vendor

The result points directly to the crontab.xml and usually the module that defines it. The job definition also specifies the PHP class and method Magento runs.

This is especially useful when a job repeatedly ends with error , runs for an unusually long time or fills cron_schedule with thousands of entries and you do not yet know which extension is responsible.

$schedule->setExecutedAt(strftime('%Y-%m-%d %H:%M:%S', time()))->save();

The status should also be saved here, not just the execution time. Change the code from the above to the below:

$schedule->setStatus(Mage_Cron_Model_Schedule::STATUS_RUNNING)->setExecutedAt(strftime('%Y-%m-%d %H:%M:%S', time()))->save();

<config>
    <crontab>
        <jobs>
            <some_unique_job_code>
                <schedule>
                    <!-- every minute for example -->
                    <cron_expr>*/1 * * * *</cron_expr>
                </schedule>
                <run>
                    <model>module/observer::functionToRun</model>
                </run>
            </some_unique_job_code>
        </jobs>
    </crontab>
</config>

Thats the first step. Once that was done, you have to manually or automatically run cron.php. Its in your stores root directory. After running cron.php, you should see entries mathcing your new job in the cron_schedule table.