Backend · Senior · Theory

Several instances of a service run the same background job once a minute, and sometimes it runs twice. How would you fix this?

~4 min by voice

How to approach it

The interviewer wants to see whether you understand the nature of races in a distributed system: that a lock with a TTL doesn't guarantee a single execution, and that the real protection is idempotency plus fencing, while the lock only saves resources.

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concurrency distributed locks

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Answer by voice

The interviewer will ask this question and listen. Think out loud and ask for a hint if you need one. When you're done, pause or tap “That's my answer”. In about a minute, your score and the points you covered show up here.

Best with headphones · ~4 min