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CoursesSystem Design Foundations

Operate and Protect

The four numbers to watch, backpressure before the queue eats the memory, rate limits keyed on the right thing, and the rollout that can be undone.

Lessons
6
Exercises
35
Minutes
38

Start The Four Numbers

  1. 1

    The Four Numbers

    After this lesson you can name the four signals every service reports, alert on the ones users feel, and read a dashboard to say which component is failing rather than which one is loud.

    Fill blankMultiple choiceTapTrace
    5 exercises
    5 min
  2. 2

    Backpressure

    After this lesson you can compute how long an unbounded queue takes to kill its process, bound it, and choose what happens to the work that no longer fits: wait, shed, or slow the sender.

    DebugCode orderMultiple choiceShort answer
    5 exercises
    6 min
  3. 3

    Rate Limits and Abuse

    After this lesson you can size a token bucket, choose the key a limit is counted on, answer a limited client honestly, and tell a burst from an abuser.

    DebugFill blankMultiple choiceShort answer
    5 exercises
    6 min
  4. 4

    Rollout and Rollback

    After this lesson you can roll a change out to a slice, watch the four numbers before widening it, keep the schema compatible with the version still running, and roll back without losing data.

    DebugCode orderMultiple choice
    5 exercises
    6 min
  5. 5

    Checkpoint: Operate and ProtectCheckpoint

    Signals, backpressure, limits and rollouts for a system you have not seen before.

    DebugMultiple choiceShort answer
    7 exercises
    6 min
  6. 6

    Boss: The Notification PlatformBoss

    One design carried from the ask to the incident: the question, the estimate, the send contract, the topology, a broadcast, a provider outage that became a retry storm, the revised pipeline, and the tradeoff you have to defend.

    Code orderMultiple choiceShort answerTapTrace
    8 exercises
    9 min