Restart PHP-FPM Automatically If Server Gets Overloaded

May 28, 2019

From time to time your server may get overloaded because PHP is spawning too many workers, or its workers get hung up, and does not make more available. I had a case where this was happening daily on a server, and it was impacting my clients so much that their sites were becoming non-responsive.

To help alleviate the issue while I was troubleshooting, we wrote a script that would automatically restart PHP-FPM if the server load was deemed too high:

#!/bin/bash

LOAD=`uptime | sed -r 's/^.*average: [0-9.]+, ([0-9.]+),.*$/\1/'`
ISLOADED=`bc <<< "$LOAD > 3"`

if [ $ISLOADED -eq 1 ]
then
        echo "restarting php-fpm at a load of $LOAD"
        systemctl restart php7.2-fpm 
fi

We then added this script to run in cron every minute. With the server stabilizing, I was able to focus on troubleshooting the actual problem, without impacting live websites TOO severely.