Cron & Task Scheduling (Cron/Systemd Timers/At)
Stop cron jobs from overlapping and crushing your CPU
🧩 The Challenge
Ever had a data sync script that runs every five minutes, only to have a massive database lock cause it to hang? Before you know it, you have fifty stale processes eating all your RAM and your server is practically catatonic.
đź’ˇ The Fix
Use flock to ensure only one instance of your script runs at a time. It’s a clean way to keep your sanity without rewriting your logic to handle PID files manually.
* * * * * /usr/bin/flock -n /tmp/my-script.lock /usr/local/bin/sync-script.sh⚙️ Why It Works
Adding the -n flag makes the command exit immediately if it can’t grab the lock instead of waiting around in a queue. You keep the system stable and the latest job just skips a beat rather than stacking up.
🚀 Pro-Tip: Always point the lock file to a dedicated directory in /var/lock/ if you want to be pedantic about FHS compliance.
Linux Tips & Tricks | © ngelinux.com | 7/29/2026