Circuit Breakers
Failing fast on a broken dependency, and what you fail fast to.
2 to work through
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intermediate Multiple choice
A team proposes circuit breakers on every downstream call. What would you add, and why is the breaker not the most important control?
2 min answer -
advanced
After adding circuit breakers, a partial outage now lasts three times longer than it used to. What is likely happening?
1 min answer
3 terms in this topic
Failure Threshold
The condition that trips a circuit breaker — best expressed as a failure rate over a rolling window with a minimum request volume, not as a consecuti…
patternFallback Strategy
What a caller does instead when a circuit breaker is open — the part of the pattern that determines whether failing fast helps anyone.
conceptHalf-Open State
The circuit breaker state that allows a limited number of trial requests through to test whether a failed dependency has recovered.
Neighbouring topics
Distributed Systems
General material on partial failure, coordination and distributed reasoning.
CAP & PACELC
What you must give up during a partition, and the latency choice the rest of the time.
Consistency Models
Linearizable, sequential, causal, eventual, and the session guarantees between them.
Idempotency
Making an operation safe to repeat, because a client that times out cannot know.
Retries & Backoff
Exponential backoff, jitter, retry budgets, and how retries become the outage.
Timeouts & Deadlines
Per-hop timeouts that do not compose, and the deadline budget that replaces them.
Backpressure & Flow Control
Telling callers to slow down instead of buffering into congestion collapse.
Load Shedding
Rejecting some work deliberately so the rest can be served correctly.
Bulkheads & Isolation
Partitioning resources so one dependency cannot starve the others.
Leader Election
Agreeing who is in charge, and fencing the one who no longer is.
Consensus Protocols
Raft, Paxos and quorums — what they guarantee and what they cost.
Distributed Locking
Mutual exclusion across machines, and why it is harder than it looks.
Distributed Transactions
Two-phase commit, its blocking failure mode, and when it is still reasonable.
Sagas & Compensation
Replacing atomicity with semantic undo, and ordering the irreversible steps last.
Service Discovery
Finding a healthy address for something whose instances are ephemeral.
Messaging & Queues
Decoupling producer from consumer, and the semantics that come with it.
Event Streaming
Retained ordered logs, consumer offsets, partitions and replay.
Clocks & Ordering
Why wall clocks lie, and how logical clocks and versions restore order.
Failure Modes
Slow rather than down, partial, grey, and failing while reporting success.