Containing Failure
A circuit breaker stops a service from hammering a downstream dependency that is already failing. In a mesh, the proxy enforces this so the protection is consistent everywhere.
How It Trips
- The proxy tracks errors and slow responses to a destination.
- When failures cross a threshold, the circuit opens and new calls fail fast.
- After a cooldown, a few probe requests test if the destination recovered, the half open state.
Failing fast is the point. A request that would have timed out after thirty seconds is rejected instantly, freeing threads and connections.
Connection Limits
The mesh also caps concurrent connections and pending requests to a destination. Outlier detection ejects an individual unhealthy endpoint from the load balancing pool while keeping healthy ones in service.
Why It Saves the System
Without breaking, a slow dependency soaks up callers threads until they too stall, and the failure spreads. The breaker turns a slow cascade into a fast, contained, recoverable error.
Key idea
A mesh circuit breaker fails fast when a downstream is unhealthy and ejects bad endpoints, turning a creeping cascade into a contained, recoverable error.