Circuit Breakers Stop the Hammer

Concepts covered: paCircuitBreaker

Retries protect against momentary failures of a single request. A circuit breaker protects against sustained failures of an entire downstream service. The motivating problem is the case where every request is failing. A retry budget keeps issuing requests, each one more painful for the downstream than the last. The downstream has been overloaded for fifteen minutes; sending more requests is not helpful. The circuit breaker pattern, popularized by Michael Nygard's book Release It, says: if the downstream has been failing consistently for some window, stop calling it for a while. The pattern fits in a few lines of state but it is the difference between a partner outage that lasts twenty minutes and one that lasts six hours. The Three States Why Failing Fast Is the Win An open breaker fails i

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