服务治理-Resilience4j（限流）

Bulkhead

Bulkhead一般用于服务调用客户端，用于限定对特定的服务的并发请求数量，起到一下作用：
1、防⽌下游依赖被并发请求冲击
2、防⽌发⽣连环故障

1、配置规则“order”

//允许最大的并发数量
resilience4j.bulkhead.backends.order.max-concurrent-call=1
//阻塞线程的最大时间量
resilience4j.bulkhead.backends.order.max-wait-time=5

2、注解方式使用

@PostMapping("/order")
    @io.github.resilience4j.circuitbreaker.annotation.CircuitBreaker(name = "order")
    @io.github.resilience4j.bulkhead.annotation.Bulkhead(name = "order") public CoffeeOrder createOrder() { NewOrderRequest orderRequest = NewOrderRequest.builder() .customer("Li Lei") .items(Arrays.asList("capuccino")) .build(); CoffeeOrder order = coffeeOrderService.create(orderRequest); log.info("Order ID: {}", order != null ? order.getId() : "-"); return order; }

3、使用配置注册方式

        private CircuitBreaker circuitBreaker;
    private Bulkhead bulkhead;

      //构造方法
    public CustomerController(CircuitBreakerRegistry circuitBreakerRegistry, BulkheadRegistry bulkheadRegistry) { circuitBreaker = circuitBreakerRegistry.circuitBreaker("order"); bulkhead = bulkheadRegistry.bulkhead("order"); } @GetMapping("/menu") public List readMenu() { return Try.ofSupplier( Bulkhead.decorateSupplier(bulkhead, CircuitBreaker.decorateSupplier(circuitBreaker, () -> coffeeService.getAll()))) .recover(CircuitBreakerOpenException.class, Collections.emptyList()) .recover(BulkheadFullException.class, Collections.emptyList()) .get(); }

RateLimiter

RateLimiter用于限制特定时间段内的执⾏次数，一般用于服务提供方，保护自己不受到冲击。

1、配置限流策略-“order”

//一个限制周期内可访问次数
resilience4j.ratelimiter.limiters.order.limit-for-period=3
//限制周期,每个周期之后，速率限制器将重置回limitForPeriod值
resilience4j.ratelimiter.limiters.order.limit-refresh-period-in-millis=30000 //线程等待允许执行时间 resilience4j.ratelimiter.limiters.order.timeout-in-millis=1000 //开启时间订阅 resilience4j.ratelimiter.limiters.order.subscribe-for-events=true //开启监控监控 resilience4j.ratelimiter.limiters.order.register-health-indicator=true

2、使用注解方式

@PostMapping(path = "/", consumes = MediaType.APPLICATION_JSON_VALUE,
            produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
    @ResponseStatus(HttpStatus.CREATED)
    @io.github.resilience4j.ratelimiter.annotation.RateLimiter(name = "order") public CoffeeOrder create(@RequestBody NewOrderRequest newOrder) { log.info("Receive new Order {}", newOrder); Coffee[] coffeeList = coffeeService.getCoffeeByName(newOrder.getItems()) .toArray(new Coffee[]{}); return orderService.createOrder(newOrder.getCustomer(), coffeeList); }

3、使用配置注册方式

    private RateLimiter rateLimiter;
    //构造方法
    public CoffeeOrderController(RateLimiterRegistry rateLimiterRegistry) { rateLimiter = rateLimiterRegistry.rateLimiter("order"); } @GetMapping("/{id}") public CoffeeOrder getOrder(@PathVariable("id") Long id) { CoffeeOrder order = null; try { order = rateLimiter.executeSupplier(() -> orderService.get(id)); log.info("Get Order: {}", order); } catch (RequestNotPermitted e) { log.warn("Request Not Permitted! {}", e.getMessage()); } return order; }