What is a cache stampede and how do you prevent it?
PICTURE THIS: STACK VS QUEUE
Simple meaning
A stampede happens when a hot key expires and many Node processes hit MongoDB at once.
WHY — Caching instead of guessing?
Why interviewers care about Caching:
who only read docs from people who shipped.
and tied to Full Stack work.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1A stampede happens when
a hot key expires and many Node processes hit MongoDB at once.
- 2Mitigations include locking on
refresh, serving stale data while rebuilding, and jittered TTLs.
- 3This is a classic
production incident for popular GET endpoints.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
A stampede happens when a hot key expires and many Node processes hit MongoDB at once. Mitigations include locking on refresh, serving stale data while rebuilding, and jittered TTLs.