Problems / Real world, medium
Each live segment is transcoded into several renditions: about 1.5 s per segment, 20 segments a second, on 24 transcoder slots.
Unlock it once for 15 credits; everything inside it is free (runs, changes, Submit, results, hints). Sign in with Google to start; new accounts get free credits.
Success ≥ 99%, p99 ≤ 5 s.
Like a coding problem, a solution has to pass every case, not just the one it was built for. Submit in the lab runs all 5; 2 of them are hidden until then.
20 requests a second for 30 seconds: 100% writes.
What each component does in this design, and what calls it. The simulator mimics each one from these settings.
| Component | Its job here | Settings |
|---|---|---|
| Load balancerLoad balancer | Traffic enters here.Calls Ingest.Layer 4 balancers route by IP and port; layer 7 balancers read HTTP and can route by path or header. | – |
| IngestApp service | Load balancer forwards to it.Calls Live transcoders.Little's law: throughput ≈ concurrency ÷ latency. 200 slots at 50 ms serve about 4,000 req/s. | 3 replicas × 200 slots · timeout 4.0 s |
| Live transcodersVideo transcoder | Ingest calls it.Transcoding turns one video into several resolutions for adaptive streaming. | 24 slots |