Helpful cPanel included application

cPanel may have some very annoying bugs sometimes however there are very useful bits of it that can help in general system administration, dealing with a very busy server and trying to terminate an account that has high disk usage will make the load averages go sky high however thanks to this neat little application provided with cPanel, you can forget about freaking out on high server load. I have personally tried multiple solutions (including nice) but the loads would still go high and the server would be unusable.

With every cPanel installation, there is a binary located at /usr/local/cpanel/bin/cpuwatch, what cpuwatch does is that it executes the command and monitors the load, if the load goes past the set limit, it will stop the application and resume it after the load averages are below the threshold for a few seconds, the usage for it is very simply

cpuwatch (<-p PID>| [arguments])
maxload : system load at which throttling should commence
command : command to run under cpuwatch
-p PID : monitor and throttle the existing process PID

Another neat feature is that it can fork a new process or attach itself to a running process, here is an example of deleting an account using SSH and setting the load average threshold to 4.0

/usr/local/cpanel/bin/cpuwatch 4.0 /scripts/killacct username

The load average will go past 4 however the process will stop running as it goes past that limit, if you already have a process running and you do not want to restart it all, you can run the following command to attach it to the process, in this case, the process ID of my process is 18274.

/usr/local/cpanel/bin/cpuwatch 4.0 -p 18274

It’s a very simple but very neat utility that has saved me a few times where I had to do major file operations and did not want the server to have high load averages, this same binary is also used when the logs are running for cPanel and as well as when the cPanel backups are running.