PHP - 限制cron作业与flock（） [英] PHP - Restrict cron job overlap with flock()

问题描述

我有一个php脚本来处理和创建大量的图像，每5分钟使用cron作业运行。我想能够限制这一点，所以它只能运行一次，而不是重叠，如果每次运行需要超过5分钟。

flock（）似乎是实现这个的最好方法，但我很难理解我应该如何添加这到我现有的脚本。我的cron作业设置为运行以下文件 -

images.php：

  $ array = array（Volvo，BMW，Toyota，Audi，Ford，Alfa，Porsche，Mercedes）; 
 
 foreach（$ array as $ car）{
 generateImageCustomFunction（$ car）; 
} 
  

我想使用非阻塞锁， p>

  $ fp = fopen（'/ tmp / lock.txt'，'r +'）; 
 
 if（！flock（$ fp，LOCK_EX | LOCK_NB））{
 echo'无法获取锁'; 
 exit（-1）; 
} 
 
 fclose（$ fp）; 
  

`lock.txt'只是一个存储/表示锁的纯文本文件，实际文件我试图运行 - 在这种情况下 images.php ？

也在哪里我真的坚持我现有的代码在

解决方案

您的代码在这里：

  $ fp = fopen（'/ tmp / lock.txt'，'w'）; 
 
 if（！flock（$ fp，LOCK_EX | LOCK_NB））{
 echo'无法获取锁' 
 exit（-1）; 
} 
 
 //您的代码
 sleep（5）; 
 
 fclose（$ fp）; 
  

lock.txt 您需要对此文件的写访问权限才能创建它。并为您的锁定文件使用唯一的名称，因此不会干扰其他进程。

I have a php script that processes and creates lots of images which is being run every 5 minutes using cron job. I want to be able to limit this so it can only run once at a time and not overlap if each run takes longer than 5 minutes.

flock() seems like the best way to achieve this but i am struggling to understand how exactly i should add this into my existing script. My cron job is setup to run the following file -

images.php:

$array=array("Volvo","BMW","Toyota","Audi","Ford","Alfa","Porsche","Mercedes");

foreach ($array as $car) {
   generateImageCustomFunction($car);
}

I want to use a non blocking lock so based on the examples:

$fp = fopen('/tmp/lock.txt', 'r+');

if(!flock($fp, LOCK_EX | LOCK_NB)) {
    echo 'Unable to obtain lock';
    exit(-1);
}

fclose($fp);

Is `lock.txt' just a plain text file that stores/indicates the lock or is that the actual file i'm trying to run - in this case images.php?

Also where about do i actually stick my existing code in the above?

解决方案

Your Code goes here:

$fp = fopen('/tmp/lock.txt', 'w');

if(!flock($fp, LOCK_EX | LOCK_NB)) {
    echo 'Unable to obtain lock';
    exit(-1);
}

// YOUR CODE HERE    
sleep(5);

fclose($fp);

lock.txt just holds your lock. You need write access to this file to create it in the first place. And use a unique name for your locking file, so it doesn't interfere with other processes.

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