The 3 a.m. Mystery

Sarah: Morning team! I've been working on the billing microservice all week. We've finally cleaned up the old codebase and replaced the ugly monolith with a clean greenfield service in Denver.
James: That sounds great, Sarah. I've been experimenting with a new caching layer lately. It's been taking ages because of some unexpected side effect with our database connections.
Olivia: Morning everyone! While you're both coding away, I've been dealing with a total infrastructure nightmare. Our staging server in Seattle has been stalling every single night at exactly 3 a.m.
Sarah: Really? Have you been digging into the logs to see what's happening? It sounds like a nasty code smell somewhere.
James: Or maybe a bad spike in traffic from our European users during overlap hours when everyone's online together.
Olivia: I've checked everything! I've been staring at CPU graphs for three days straight. It's not traffic and it's not our code.
Sarah: That's bizarre. Could it be an external service trying to sync data while we're all offline?
James: Maybe someone left a heavy background cron job running on the cluster before they went on leave last week.
Olivia: Guess what? I checked the office security cameras this morning. It's not a cron job at all.
Sarah: Wait, don't tell me. Is someone mining crypto in the server room again?
Olivia: No! It's the new office cleaning robot. It connects to Wi-Fi at 3 a.m. every night and downloads a massive 50-gigabyte software update right next to the rack.
James: You're kidding! Our entire staging environment has been crashing because of a vacuum cleaner?
Sarah: That's hilarious. Well, at least we've solved the mystery. Let's put that robot on our async-first blacklist!
Olivia: Exactly. I've already unplugged its base station. We can finally get some sleep tonight.

Read again and choose the right answer

What has Sarah been working on this week?

• The billing microservice
• A cleaning robot
• A database caching layer

At what time does the server stall every night?

• Midnight
• 3 a.m.
• 5 p.m.

What is actually causing the CPU spike?

• A heavy cron job
• European user traffic
• The office cleaning robot

What does Olivia do at the end of the story?

• Unplugs the robot's base station
• Rewrites the codebase in Rust
• Goes on leave for a week

Sources: photo by Christina Morillo on Pexels