php文件排他锁

<?php$fp = fopen("test.php", "r");if(flock($fp,LOCK_EX | LOCK_NB)){    echo ‘111111111111‘;    ob_flush(); // 清空缓存立即输出    flush();    sleep(10);    //..处理订单    flock($fp,LOCK_UN);}else{    ob_flush();    flush();    echo "做些其他业务逻辑";    echo "系统繁忙，请稍后再试";}

fclose($fp);