이벤트의 지속 가능성에 대해

<?php
$base = event_base_new();
$event = event_new();

event_set($event,STDIN,EV_READ | EV_PERSIST,&#39;print_line&#39;,[$event,$base]);

event_base_set($event,$base);
event_add($event,5000000);
event_base_loop($base);

function print_line($fd, $events, $arg)
{
    // 5秒超时会自动输出1，每次执行了read后，超时会被重置
    echo 1;
    static $max_requests = 0;
    $max_requests++;
    if ($max_requests == 10) {
        // $arg[1] = $base
        event_base_loopexit($arg[1]);
    }
    // 打印输出
    echo  fgets($fd);
}