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Notes / Docker Sandboxes / Distributed Caching: Two-Tier L1/L2 Cache Invalidation & Consistency
Docker Sandboxes · Tier 2: Data & Scale · Lab 74

Distributed Caching: Two-Tier L1/L2 Cache Invalidation & Consistency

Why do high-throughput architectures add an in-process RAM cache (L1) in front of Redis (L2)? Measure sub-millisecond in-memory read latencies, reproduce silent cache drift where Node 2 serves stale prices after Node 1 updates, and broadcast real-time cache evictions across the cluster using Redis Pub/Sub with version fencing.

Time25 minutes
StackRedis 7Ports 18410, 18411, 18412, 18413
MemoryAbout 180 MB
Before thisLab 06Redis Basics
Download lab (.zip) View steps
Verified runWindows, Mac, LinuxBash and PowerShell
  1. 1PrepareWhat you will learn
  2. 2PredictGuess before you run
  3. 3RunStep by step
  4. 4ObserveWhat you should see
  5. 5Break itChange one thing
  6. 6Clean upLeave nothing running
On this page
  1. 00 / What You Will Learn
  2. 01 / Why It Matters
  3. 02 / What We Are Building
  4. 03 / Words You Need
  5. 04 / Predict First
  6. 05 / Step by Step
  7. 06 / What You Should See
  8. 07 / Look Inside
  9. 08 / Break It, Fix It
  10. 09 / In Real Projects
  11. 10 / Interview Corner
  12. 11 / Clean Up

00 /What You Will Learn

By the end you will be able to
  • Construct a two-tier caching hierarchy: combine in-process container RAM (L1) with distributed Redis 7 (L2) and PostgreSQL.
  • Measure the latency advantage: compare 0.02 millisecond L1 memory lookups against 1.5 millisecond network cache hops.
  • Reproduce silent cache drift: observe how multi-instance clusters serve stale data when in-memory caches miss update events.
  • Broadcast real-time cache invalidation across cluster instances using Redis Pub/Sub.
  • Prevent out-of-order race conditions using monotonic version fencing so delayed reads cannot resurrect evicted cache state.

Before you start

Complete Lab 06 (Redis Basics) and Lab 14 (Redis Cache-Aside & Eviction) first. You should understand key-value lookups, TTL expiry, and pub/sub messaging. Docker Desktop must be running.