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Time, Failure & Delivery

Failure detectors and heartbeats, clock skew and logical clocks, delivery semantics and idempotency, and the retry patterns that prevent cascading failure.

1
How do you decide a node is dead — and why is 'dead' fundamentally undecidable?
senior
✓
2
Why can't you order events by `System.currentTimeMillis()` across machines?
staff
✓
3
Lamport timestamps vs vector clocks — what can each tell you, and what can't they?
staff🎬 animated
✓
4
Is exactly-once delivery possible? Design a payment consumer that never double-charges.
senior
✓
5
A downstream service slows down and your whole platform goes with it. What went wrong, and how do you stop it?
senior
✓

How do you decide a node is dead — and why is 'dead' fundamentally undecidable?

Why can't you order events by `System.currentTimeMillis()` across machines?

Lamport timestamps vs vector clocks — what can each tell you, and what can't they?

Is exactly-once delivery possible? Design a payment consumer that never double-charges.

A downstream service slows down and your whole platform goes with it. What went wrong, and how do you stop it?