```php
$worker->onWorkerStart = function($worker)
{
// 将db实例存储在全局变量中(也可以存储在某类的静态成员中)
global $db1;
global $db2;
global $db3;
...
$db1 = new \Workerman\MySQL\Connection('host', 'port', 'user', 'password', 'db_name1');
$db2 = new \Workerman\MySQL\Connection('host', 'port', 'user', 'password', 'db_name2');
$db3 = new \Workerman\MySQL\Connection('host', 'port', 'user', 'password', 'db_name3');
...
};
```