php使用flock阻塞写入文件和非阻塞写入文件

阻塞写入代码：（所有程序会等待上次程序执行结束才会执行，30秒会超时）

<?php  
$file = fopen("text.txt","w+");  
$t1 = microtime(TRUE);  
if (flock($file,LOCK_EX))  
{  
  sleep(30);  
  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));  

非阻塞写入代码：（只要文件被占用，则显示Error locking file!）

<?php  
$file = fopen("text.txt","a+");  
  
$t1 = microtime(TRUE);  
if (flock($file,LOCK_EX|LOCK_NB))  
{  
  sleep(30);  
  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));  

Error locking file!0.000096

Ok locking file!30.002354