declare控制程序執行時間,多少秒超時後退出

<?php

declare(ticks = 1);

$timeStart = time();

function checkTimeout () {
    global $timeStart;
    $seconds = 1;

    if (time() - $timeStart > $seconds) {
        exit ('超時' . "\n");
    }   
}

register_tick_function('checkTimeout');

while (1) {
    echo '1<br>';
}