Dealing with “The Black Shadow”
Alright, let me tell you about this thing we started calling “the black shadow”. It wasn’t like a ghost, you know, but it sure felt like one haunting our servers for a good few weeks.
It started subtle. We’d see these weird spikes in resource usage, like CPU or memory just jumping up for no reason. No errors logged, nothing crashed. It just… happened. Then, poof, gone. Like a shadow flickered across the monitors. Happened maybe once a day, sometimes less, sometimes more. Totally unpredictable.
First thing I did, naturally, was dive into the logs. Hours spent digging through system logs, application logs, database logs. Found nothing. Absolutely zero indication of what was causing these spikes. It was like the system itself didn’t even know it was happening.
Next step, I beefed up the monitoring. Put extra watchers on everything. CPU, RAM, disk I/O, network traffic, specific process behavior. I sat there, watching the graphs like a hawk. And guess what? The moment I was actively watching, trying to catch it red-handed? Nothing happened. It was almost shy. Or maybe just mocking me.
We started throwing theories around:
- Maybe it’s a backup process gone rogue? Checked those. Schedules were fine, logs looked normal.
- A weird database query locking things up? Ran diagnostics, checked slow query logs. Nope.
- Network hiccup? Talked to the network guys. They saw nothing unusual from their end.
- Some hidden cron job someone forgot about? Scoured the crontabs. Found some old stuff, cleaned it up, but the shadow remained.
It was getting seriously annoying. Not because it was breaking things (it wasn’t, yet), but because we couldn’t explain it. It was this unknown factor, this little black shadow lurking in the corner of our system’s eye. Felt like driving with a weird noise coming from the engine – maybe it’s nothing, maybe you’re about to break down.
The breakthrough, when it finally came, was almost anticlimactic. I was tracing dependencies for a completely unrelated service we were planning to update. Deep in the config files of an old, almost forgotten internal tool, I found it. There was this tiny utility, supposed to run once a week to generate some report nobody looked at anymore. But its configuration was messed up. Instead of weekly, due to a typo in the scheduling syntax (something really dumb, like a misplaced comma or asterisk), it was trying to run almost randomly, triggered by certain system events rather than time. And when it ran, it went nuts for a few minutes trying to pull way too much data, hence the spike.
Disabled the stupid thing. Just switched it off. And the black shadow? Gone. Vanished.
Weeks of scratching our heads, suspecting complex issues, digging through layers of logs and monitors. And it was just a typo in a config file for a useless tool. Felt kind of stupid afterwards, but also relieved. That’s how it goes sometimes, doesn’t it? You hunt for elephants and find a mouse hiding under the rug. At least the shadow was gone.
