spring cloud learning - 13. Circuit Breaker: Hystrix Clients

13. CircuitBreaker: Hystrix Clients

Hystrix

breaker

13.1 How to Include Hystrix

The service consumer microservice-customer-movie-ribbon-withHistrict2 writes the circuit breaker above.

If the service provider microservice-provider-user is abnormal, a short circuit will occur and the written program will be executed

1. Add the annotation @EnableCircuitBreaker to the startup class

2.controller

@controller
@RestController
public class UseDemoController {

	@Autowired
	private RestTemplate restTemplate;
	
	@RequestMapping("/demo")
	@HystrixCommand(fallbackMethod = "findByIdFallback")//Set the circuit breaker, if it cannot be connected, execute the circuit breaker "findByIdFallback"
	public String useDemo () {
		return restTemplate.getForObject("http://microservice-provider-user/demo/dd", String.class);//Parameter 1 makes eureka's service-id, which is a virtual host name, you can use eureka.instance.secure. virtual-host-name definition, if not https, use eureka.instance.virtual-host-name
	}
	
	// circuit breaker method
	public String findByIdFallback() {
		return " ----findByIdFallback---";
	}
}

 

13.2Propagating the Security Context or using Spring Scopes

execution.isolation.strategy  

This property indicates which isolation strategyHystrixCommand.run() executes with，one of the following two choices：隔离策略

THREAD——it executes on a separate thread and concurrent requests are limited by the number of threads in the thread-pool (it executes on a separate thread, concurrent requests are limited by the number of threads in the thread pool, the default policy)

SEMAPHORE - it executes on the calling thread and concurrent requests are limited by the semaphore count

hystrix.shareSecurityContext : spring security context

13.3 Health Indicator

/health exposes the state of connected circuit breakers

13.4 Hystrix Metrics Stream

hystrix.stream as management port