php 多线程读写入同一个文件

function T_put($filename,$string){
    $fp = fopen($filename,'a');   //追加方式打开
    if (flock($fp, LOCK_EX)){      //加写锁
        fputs($fp,$string);        //写文件
        flock($fp, LOCK_UN);       //解锁
    }
    fclose($fp);
}

function T_get($filename,$length){
    $fp = fopen($filename,'r');   //追加方式打开
    if (flock($fp, LOCK_SH)){      //加读锁
        $result = fgets($fp,$length);        //写文件
        flock($fp, LOCK_UN);       //解锁
    }
    fclose($fp);
    return $result;
}