php利用文件进行排他型锁定，防止并发

<?php

$fp = fopen(‘/tmp/file.lock‘, "a+");

if(flock($fp, LOCK_EX)) { //进行排他型锁定

    fwrite($fp, "lock success\n");
    fflush($fp); //flush output before releasing the lock
    flock($fp, LOCK_UN); //释放锁定

} else {
    echo "文件正在被其他进程占用";
}

fclose($fp);

?>