Queue It Up – mid-level system design challenge

Write traffic spikes 5× partway through. Absorb the burst without dropping a single write.

Requirements

• Traffic: 600 writes/s, bursting to 3,000
• p99 latency: ≤ 2 s
• Errors: ≤ 0.5%: every write must be kept

Goal

Hold p99 latency under 2,000ms, error rate under 0.5% through every stage of the test plan, then compare your design with a reference design.

The test plan

1. Normal: 600 requests per second.
2. 5× burst: 3,000 requests per second.
3. After the burst: 600 requests per second.

Hint

Queues never drop - they buffer. Put a queue between the API and the workers, and give the API enough instances to take the 5× burst.

Solve it on the live simulator, free and in your browser.

Read the guide

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