Problems / RAG and retrieval, hard

Multi-hop retrieval loops

An agentic retriever makes up to 8 search hops per question, and each hop hits the search service.

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Your goals

Success ≥ 95% of tasks, p99 ≤ 90 s.

The traffic

6 requests a second for 45 seconds: 100% task (writes).

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 Agent API.Layer 4 balancers route by IP and port; layer 7 balancers read HTTP and can route by path or header.–
Agent APIApp serviceLoad balancer forwards to it.Calls Agent orchestrator.Little's law: throughput ≈ concurrency ÷ latency. 200 slots at 50 ms serve about 4,000 req/s.3 replicas × 500 slots · timeout 180 s
Agent orchestratorAgent orchestratorAgent API calls it.Calls Model, Hybrid search.An agent loops: think, call a tool, read the result, repeat until done.400 slots · 8 steps
ModelLLM endpointAgent orchestrator calls it.Latency has two parts: time to the first token, then a steady stream of tokens per second.300 streams
Hybrid searchHybrid searchAgent orchestrator calls it.Hybrid search combines keyword matching (BM25) with vector similarity.40 slots · 2 steps

Hints

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

Hint 1

Count search calls per question.

Hint 2

Most questions need 2–3 hops.

One way to solve it

Cap the hops (agent steps).

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