php使用flock堵塞写入文件和非堵塞写入文件

堵塞写入代码：（全部程序会等待上次程序运行结束才会运行，30秒会超时）

<?php
$file = fopen("test.txt","w+");

$t1 = microtime(TRUE);
if (flock($file,LOCK_EX))
{
  sleep(10);
  fwrite($file,"Write something");
  flock($file,LOCK_UN);
  echo "Ok locking file!";
}
else
{
  echo "Error locking file!";
}

fclose($file);

$t2 = microtime(TRUE);
echo sprintf("%.6f",($t2-$t1));

<?
php
$file = fopen("test.txt","a+");

$t1 = microtime(TRUE);
if (flock($file,LOCK_EX|LOCK_NB))
{
  sleep(10);
  fwrite($file,"Write something");
  flock($file,LOCK_UN);
  echo "Ok locking file!";
}
else
{
  echo "Error locking file!";
}

fclose($file);

$t2 = microtime(TRUE);
echo sprintf("%.6f",($t2-$t1));