Golang implements circuit breaker

With the popularity of microservice architecture, the circuit breaker mechanism has become an indispensable part. The circuit breaker mechanism can avoid the impact of some network or service failures on the entire system and ensure the reliability and stability of the system. This article will introduce how to use Golang to implement circuit breaker.

What is a circuit breaker?

In a distributed system, communication between services may face problems such as network fluctuations, hardware failures, and timeouts. If the transmission anomaly caused by the fault is not discovered and handled in time, it will cause part or the entire system to collapse, causing serious consequences. The emergence of the circuit breaker mechanism solves this problem.

Circuit breaking is a mechanism to deal with failures. When a service fails, the circuit breaker mechanism will quickly disconnect the service call and set a time window. Within this time window, any request for the service will be intercepted directly and an error message will be returned, avoiding the impact of an avalanche failure on the called service and allowing the system to continue operating until the service returns to normal.

Golang implements circuit breaker

Golang is an efficient, concise and easy-to-learn language, suitable for the development of distributed systems. The integrated environment of the Go language already contains many circuit breaker libraries, which are very convenient to use.

The following will introduce how to use Golang to implement circuit breaker.

Install the circuit breaker library

In Golang, the circuit breaker mechanism is usually implemented using a circuit breaker. In order to use the circuit breaker mechanism, the circuit breaker library needs to be installed first. More practical libraries include Netflix's Hystrix and go-kit's circuit breaker library.

Here we take the circuit breaker library of go-kit as an example to explain. First you need to install it into your local environment. Execute the following code in the terminal:

go get github.com/go-kit/kit/v2/circuitbreaker

Using the circuit breaker library

After installing the circuit breaker library, you can start using the circuit breaker. The following describes how to use go-kit's circuit breaker library to implement circuit breaker.

Define a fuse

The process of defining a fuse is very simple, just use the following code:

breaker := circuitbreaker.NewCircuitBreaker(circuitbreaker.Config{
  Timeout:      2 * time.Second, // 超时时间
  MaxRequests:  1, // 最大请求数
  ReadyToTrip: func(counts circuitbreaker.Counts) bool {
    return counts.ConsecutiveFailures > 3 // 连续3次失败后打开断路器
  },
})

Among them, Timeout specifies the requested Timeout; MaxRequests restricts the maximum number of requests within a time period; ReadyToTrip function is used to check whether the circuit breaker needs to be opened. In the above code, when a request fails more than 3 times, the ReadyToTrip function will return true, that is, open the fuse.

Calling the fuse

After defining the fuse, you can start calling the service. Assuming that you want to call a service, you can implement it as follows:

func main() {
  breaker := circuitbreaker.NewCircuitBreaker(circuitbreaker.Config{
    Timeout:      2 * time.Second,
    MaxRequests:  1,
    ReadyToTrip: func(counts circuitbreaker.Counts) bool {
      return counts.ConsecutiveFailures > 3
    },
  })
  
  if err := breaker.Call(func() error {
    // 调用远端服务
    return remoteCall()
  }); err != nil {
    // 熔断后的处理
    fmt.Println("断路器已开启：", err)
  }
}

When you actually call the service, encapsulate it in the breaker.Call() function. If an error occurs in the call, the circuit breaker mechanism will be triggered, and fault tolerance can be implemented in the code.

Summary

This article introduces the basic definition and principle of the circuit breaker mechanism, and explains in detail how to use Golang to implement circuit breaker. In the development of distributed systems, the circuit breaker mechanism is a very important function. The introduction of the circuit breaker mechanism can ensure the high availability and stability of the system, and plays a vital role in avoiding system crashes.

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