swoole_timer模組提供了非同步毫秒定時器，可用於心跳包傳送。

$client = new swoole_client(SWOOLE_SOCK_TCP, SWOOLE_SOCK_ASYNC); //非同步非阻塞
$client->on("connect", function(swoole_client $cli){});
$client->on("receive", function(swoole_client $cli, $data){});
$client->on("error", function(swoole_client $cli){});
$client->on("close", function(swoole_client $cli){});
$client->connect('127.0.0.1', 5001);
swoole_timer_add(150000, function () use ($client) {
      $client->send('beatheart');
});