You could start your php script from the command line (i.e. bash) by using
nohup php myscript.php &
the & puts your process in the background.
Edit:
Yes, there are some drawbacks, but not possible to control? That's just wrong.
A simple kill processid will stop it. And it's still the best and simplest solution.
You could start your php script from the command line (i.e. bash) by using
nohup php myscript.php &
the & puts your process in the background.
Edit:
Yes, there are some drawbacks, but not possible to control? That's just wrong.
A simple kill processid will stop it. And it's still the best and simplest solution.
Another option is to use Upstart. It was originally developed for Ubuntu (and comes packaged with it by default), but is intended to be suitable for all Linux distros.
This approach is similar to Supervisord and daemontools, in that it automatically starts the daemon on system boot and respawns on script completion.
How to set it up:
Create a new script file at /etc/init/myphpworker.conf. Here is an example:
# Info
description "My PHP Worker"
author "Jonathan"
# Events
start on startup
stop on shutdown
# Automatically respawn
respawn
respawn limit 20 5
# Run the script!
# Note, in this example, if your PHP script returns
# the string "ERROR", the daemon will stop itself.
script
[ $(exec /usr/bin/php -f /path/to/your/script.php) = 'ERROR' ] && ( stop; exit 1; )
end script
Starting & stopping your daemon:
sudo service myphpworker start
sudo service myphpworker stop
Check if your daemon is running:
sudo service myphpworker status
Thanks
A big thanks to Kevin van Zonneveld, where I learned this technique from.
As others have noted, various versions of PHP have issues with their garbage collectors. Of course, if you know that your version does not have such issues, you eliminate that problem. The point is, you don't know (for sure) until you write the daemon and run it through valgrind to see if the installed PHP leaks or not on any given machine. So on that hand, you may write it just to discover that what Zend thinks is fixed might still be buggy, or you are dealing with a slightly older version of PHP or some extension. Icky.
The other problem is somewhat buggy signals. In my experience, signal handlers are not always entered correctly with PHP, especially when the signal is queued instead of merged. That may not be an issue for you, i.e. if you just need to handle SIGINT/SIGUSR1/SIGUSR2/SIGHUP.
So, I suggest:
If the daemon is simple, go ahead and use PHP. If it looks like its going to get rather complex, or allocate lots of memory, you might consider writing it in C after prototyping it in PHP.
I am a pretty die hard C person. However, I see nothing wrong with hammering out something quick using PHP (beyond the cases that I explained). I also see nothing wrong with using PHP to prototype something that may or may not be later rewritten in C. For instance, handling database stuff is going to be much simpler if you use PHP, versus managing callbacks using other interfaces in C. So in that instance, for a 'one off', you will surely get it done much faster.
I would be inclined to perform this task with a cron job, rather than polling the database in a daemon.
It's likely that your FFmpeg command will take a while to do it's thing, right? In that case, is it really necessary to be constantly polling the database? Wouldn't a cronjob running each minute (or every five, ten or twenty minutes for that matter) be a simpler way to achieve the same thing?