The circuit breaker.
A fuse that trips so a failing service can’t drag the rest down with it.
- Try again… again… again…1
One service keeps calling a dependency that has started failing.
- 2
A breaker sits in the middle, watching the failure rate.
- Open. Stop calling.3
Too many failures and it trips: calls stop, and they fail instantly instead.
- 4
Failing fast spares both sides — and gives the sick service room to recover.
- One probe…5
After a pause it lets a single test call through to check (half-open).
- 6
Healthy again? It closes, and normal traffic resumes.
Semicolony semicolony.dev/eli5/circuit-breaker/comic