David Young

Interactive engineering / Six connected experiments

Make a change. See the consequence.

Start with failure and recovery. Follow the system through caching, storage, load, and architecture. Finish with a fresh design brief.

A connected learning path

From safe retries to a full design.

Follow work through failure, caching, storage choices, capacity, and architectural growth. Finish by designing a fresh scenario. Each lesson ends with a short check grounded in its experiment.

0 / 6lessons complete
  1. 01
    Failure simulator6 min

    Survive the second attempt

    Crash a worker after a provider call. Replay delivery and see how durable claims and idempotency keys change the outcome.

    Try thisCrash after the provider effect. Turn off provider keys and replay delivery two.
    Start here
    Step 1
  2. 02
    Systems sandbox8 min

    Speed up without changing truth

    Route requests between instances, then run continuous traffic to see hits, misses, hot keys, and stale decisions.

    Try thisWarm both instances, revoke access, then compare TTL-only with write-time invalidation under traffic.
    Open lab
    Step 2
  3. 03
    Decision playground10 min

    Choose data paths by the question

    Compare six storage models against one workload. Mutate sample data, run an access path, and inspect load-sensitive tradeoffs.

    Try thisPick media files, then switch the primary query to relationships. Watch the preferred model change.
    Open lab
    Step 3
  4. 04
    Linked calculator8 min

    Follow load through the system

    Turn users into peak traffic, app instances, database work, connection demand, cache memory, and storage.

    Try thisPick the busy chat preset. Lower the cache hit rate, then test whether the application pool fits the database ceiling.
    Open lab
    Step 4
  5. 05
    Architecture walkthrough9 min

    Change the constrained part

    Grow an architecture through seven stages. Inject traffic and failures to see what each step fixes and what it adds.

    Try thisCompare stages 2 and 3 at the same load. Then lose an app instance at stage 4.
    Open lab
    Step 5
  6. 06
    Practice generator15 min

    Put the decisions together

    Generate a product, scale, and hard constraint. Sketch a design, reveal hints when needed, and test your own explanation.

    Try thisLock the product, generate a new scale, and explain which data and failure choices now change.
    Open lab
    Step 6
Put it together

Use the final practice generator to combine the decisions in a new product, scale, and failure scenario.

Continue: Retry & Idempotency Lab