How to execute multiple crontab inside onWorkerStart .

```
$crontab_worker->onWorkerStart = function ($crontab_worker) use ($app) {
new Crontab('0 0 * * *', $app->boot('/article/sitemap/main'),'sitemap');
new Crontab('*/15 * * * *', $app->boot('/multimedia/migration'),'migration_image');
new Crontab('*/19 * * * *', $app->boot('/article/migration'),'migration_article');
};
````

as you can see, if we execute multiple crontabs there, the memory usage keeps increasing. I am not sure if it's the right way to execute multiple crontab all at once.