Systems · Week 1
Week 1: Foundations under load
Presence, pools, cache storms, async pipelines, and log streams — control load before it controls you.
Week 1: Foundations under load
Presence, pools, cache storms, async pipelines, and log streams — control load before it controls you.
Outcomes
- Explain the failure drill for each lesson in this week without notes.
- Complete linked labs where present and keep a short metric log.
- Tag each system with the pattern cards you actually used.
- Connection pools mental models Why pool size, wait queues, and timeouts dominate latency more than raw QPS.
- Presence and online indicators Heartbeat TTL maps that stay honest under disconnects and clock skew.
- Async pipelines and backpressure Queues that protect producers from drowning consumers — and vice versa.
- Cache miss storms Single-flight and soft TTL stop a cold key from melting the origin.
- Log streamer and append-only feeds Serving a growing event stream without rewriting history.