Question 1

How to export cep21/circuit metrics to Prometheus?

Accepted Answer

Circuit supports Prometheus through the prometrics collector. Configure it in the circuit config's Metrics collectors, as shown in the custom metrics example, allowing direct scraping of circuit health and performance data into Prometheus.

Question 2

cep21/circuit vs sony/gobreaker: which is better for Go?

Accepted Answer

Choose cep21/circuit if you need Hystrix compatibility, advanced metrics, or SLO tracking; it's feature-rich but more complex. Sony/gobreaker is lighter and simpler, ideal for basic circuit breaking without extra overhead, though benchmarks show Circuit is efficient.

Question 3

How to set up a fallback function in cep21/circuit?

Accepted Answer

Pass a fallback function to the Execute method; the README provides an example where it returns nil on failure. You can customize logic based on error types, enabling graceful degradation when the circuit is open or errors occur.

Question 4

Does cep21/circuit handle context cancellation properly?

Accepted Answer

Yes, it integrates with Go's context.Context for timeouts and cancellations. By default, early terminations from context cancellation aren't counted as circuit failures, but this can be adjusted with the IgnoreInterrupts flag, as detailed in the examples.

Question 5

What's the memory footprint of cep21/circuit in production?

Accepted Answer

Benchmarks show low memory allocation, with minimal configs achieving zero allocs per op. However, enabling features like Hystrix dashboard streaming or custom metrics increases usage based on configuration, so monitor accordingly.

Question 6

How to configure SLO tracking for response times?

Accepted Answer

Use the responsetimeslo.Factory to define a maximum healthy time, then add it to the Manager's DefaultCircuitProperties. This tracks the percentage of requests faster than the threshold, providing SLO health metrics, as illustrated in the example.

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