Problems / LLM serving, hard

Batch inference used for live traffic

Live requests were routed to a batch-inference queue meant for offline jobs: it holds requests for 30+ seconds.

Free to open. Runs in your browser, no sign-up.

Your goals

Success ≥ 99%, p99 ≤ 5 s.

The traffic

20 requests a second for 30 seconds: 100% request (reads).

The system

What each component does in this design, and what calls it. The simulator mimics each one from these settings.

ComponentIts job hereSettings
Load balancerLoad balancerTraffic enters here.Calls AI app.Layer 4 balancers route by IP and port; layer 7 balancers read HTTP and can route by path or header.–
AI appApp serviceLoad balancer forwards to it.Calls Real-time GPU pool.Little's law: throughput ≈ concurrency ÷ latency. 200 slots at 50 ms serve about 4,000 req/s.3 replicas × 500 slots · timeout 30 s
Real-time GPU poolSelf-hosted serving poolAI app calls it.GPU servers batch requests together; throughput rises with batch size until memory runs out.8 slots

Hints

Try it first. Open one hint at a time if you get stuck.

Hint 1

Batch APIs trade latency for price.

Hint 2

Nothing is overloaded; it’s just slow.

One way to solve it

Serve live traffic from a real-time endpoint: give it the capacity, keep batch for offline work.

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