How circuit is closed again?

There are actually three states: OPEN, CLOSED, and HALF_OPEN. Once the circuit breaker is OPEN and a certain amount of time has passed it lets a single request sneak through. This is the HALF_OPEN state. If successful the circuit breaker is closed, otherwise it returns to the OPEN state until that amount of time has passed again, where it enters the HALF_OPEN state once again. You can specify the amount of time between the transition to OPEN to HALF_OPEN using the circuitBreaker.sleepWindowInMilliseconds property.