熔断器弹性架构

Architecture

熔断器弹性架构图，展示完整的状态机，包括关闭、打开和半开状态、故障阈值跟踪、恢复计时器以及保护服务免受级联故障的降级响应策略。该模板详细可视化熔断器模式，包括熔断器如何根据成功和失败计数在状态之间转换。对于构建在负载下优雅降级的容错微服务至关重要。

下载 .fz 文件

完整 FlowZap 代码

Client { # Client Service
n1: circle label:"Service Call"
n2: rectangle label:"Circuit Breaker Proxy"
n3: rectangle label:"Receive Response"
n4: circle label:"End"
n1.handle(right) -> n2.handle(left)
n2.handle(bottom) -> Breaker.n5.handle(top) [label="Check State"]
n3.handle(right) -> n4.handle(left)
}
Breaker { # Circuit Breaker
n5: diamond label:"Circuit State?"
n6: rectangle label:"Forward Request (Closed)"
n7: rectangle label:"Return Fallback (Open)"
n8: rectangle label:"Test Request (Half-Open)"
n9: rectangle label:"Track Success"
n10: rectangle label:"Track Failure"
n11: diamond label:"Failure Threshold?"
n12: rectangle label:"Trip Circuit Open"
n13: rectangle label:"Reset to Closed"
n14: rectangle label:"Start Recovery Timer"
n5.handle(right) -> n6.handle(left) [label="Closed"]
n5.handle(bottom) -> n7.handle(top) [label="Open"]
n5.handle(left) -> n8.handle(right) [label="Half-Open"]
n6.handle(bottom) -> Downstream.n15.handle(top) [label="Forward"]
n7.handle(top) -> Client.n3.handle(bottom) [label="Cached/Default"]
n8.handle(bottom) -> Downstream.n15.handle(top) [label="Probe"]
n9.handle(right) -> n13.handle(left) [label="Healthy"]
n10.handle(right) -> n11.handle(left)
n11.handle(right) -> n12.handle(left) [label="Exceeded"]
n11.handle(top) -> n6.handle(bottom) [label="Below"]
n12.handle(right) -> n14.handle(left) [label="Cooldown"]
n14.handle(top) -> n8.handle(bottom) [label="Timer Expired"]
}
Downstream { # Downstream Service
n15: rectangle label:"Process Request"
n16: diamond label:"Response OK?"
n17: rectangle label:"Return Success"
n18: rectangle label:"Return Error/Timeout"
n15.handle(right) -> n16.handle(left)
n16.handle(right) -> n17.handle(left) [label="200"]
n16.handle(bottom) -> n18.handle(top) [label="5xx/Timeout"]
n17.handle(top) -> Breaker.n9.handle(bottom) [label="Success"]
n18.handle(top) -> Breaker.n10.handle(bottom) [label="Failure"]
n17.handle(top) -> Client.n3.handle(bottom) [label="Response"]
}

为什么需要这个工作流？

When a downstream service fails, continuing to send requests wastes resources and can cascade failures across the entire system. The circuit breaker pattern detects failures, stops sending requests to unhealthy services, and automatically recovers when the service heals—preventing cascading failures and enabling graceful degradation.

工作原理

Step 1: The circuit breaker proxy intercepts all outbound requests to the downstream service.
Step 2: In the closed state, requests pass through normally and success/failure counts are tracked.
Step 3: When failures exceed the configured threshold, the circuit trips to the open state.
Step 4: In the open state, requests immediately return a fallback response without contacting the downstream service.
Step 5: After a recovery timer expires, the circuit enters the half-open state and sends a test request.
Step 6: If the test succeeds, the circuit resets to closed; if it fails, it returns to open.

替代方案

Simple retry logic does not prevent cascading failures. Timeout-based approaches waste resources waiting. Libraries like Resilience4j, Polly, or Hystrix implement circuit breakers. This template visualizes the complete state machine for understanding the pattern.

Key Facts

Template Name	熔断器弹性架构
Category	Architecture
Steps	6 workflow steps
Format	FlowZap Code (.fz file)