Question

I have a PHP script launched from a command-line (aka CLI mode, no webserver involved).

In this script I launch a command that will run from some time, usually exiting after a couple minutes. But at times, this command will run for hours because of various issues, and the best I can do is kill it and wait for a while before launching it again.

Two things I want to emphasize :

• I have no control of the code inside that command, and can’t improve failure detection.
• It’s not an important task, and it’s perfectly ok to have it working that way.

That being said, I would like to improve things in my code, so that I can kill the child process if the command has been running for more than N seconds. But I still want to get the return code from the command, when it runs fine.

Pseudo-code should be something like this :

Launch command
While command is running
{
    If the command is done running
    {
        echo return code
    }
    else
    {
        If the command has been running for more than N seconds
        {
            Kill the child process
        }
    }
}

How would you implement this in PHP ?

Thank you !

Solution : I ended up using the SIG_ALERT signal. More info on the signals handling and the pcntl lib in the pages provided by Gordon in his post.

Answer 1

Read through this Chapter of Practical PHP Programming.
It covers interoperating with Processes extensively. And also have a look at the PHP Manual’s pages on Process Control.

You might also be interested in Gearman

Sorry for not providing any code. I never had the need for Process Control stuff, so I just kept in memory where to look in case I’d ever need it.