How to shut down golang process

Golang is a strong runtime programming language that can be used to develop high-availability applications. However, in actual development, we may encounter the problem of process shutdown. In this case, we need to use some tools and techniques in Golang to control the shutdown of the process.

This article will cover primitives, signals and other advanced techniques for process shutdown in Golang. We will explore these topics to help you better understand how to control the shutdown of Golang processes.

Primitives for process shutdown

In Golang, the most basic way to shut down a process is to use a two-way channel or cancel the channel. Bidirectional channel is the type of channel used in Golang for communication between different Goroutines. Cancellation channels are a Golang variant of bidirectional channels that can be used to communicate and cancel tasks between Goroutines.

Here, we will use the cancellation channel to demonstrate how to control the shutdown of the process. Here is an example of using a cancellation channel to control process shutdown:

func worker(cancel chan struct{}) {
  for {
    select {
      //检查是否收到取消指令
      case <-cancel:
        log.Println("Worker: Stopping the work")
        return
      //正常工作逻辑
      default:
        log.Println("Worker: Doing some work")
        time.Sleep(time.Second * 1)
    }
  }
}

func main() {
  //创建取消通道
  cancel := make(chan struct{})
  
  //启动工作子进程
  go worker(cancel)
  
  //等待一段时间后取消工作
  time.Sleep(time.Second * 5)
  close(cancel)
  
  //等待程序退出
  time.Sleep(time.Second * 1)
}

In this example, we create a worker function to simulate a worker process. The worker function uses an infinite loop to perform work, calling the select statement each time it loops to check whether a cancellation instruction has been received. If received, print a log and return, otherwise execute normal work logic. In the main function, we create a cancellation channel, start a worker subprocess, and wait five seconds to close the cancellation channel to stop the work.

After the cancellation channel is closed, the worker function will receive a cancel signal, and then it will exit the loop and return.

Signals for process shutdown

In addition to closing the process by canceling the channel, we can also use process signals to control the shutdown of the Golang process. Signals are an operating system-level communication mechanism used to deliver messages and events within the system. In Linux systems, signals are very common. For example, when an application is executing, if it receives the SIGKILL signal, it will be forced to end. In Golang, we can use os.Signal to define signal types and os.Notify to subscribe to signal events.

The following is an example of using signals to control process shutdown:

func main() {
  //创建关闭信号
  stop := make(chan os.Signal, 1)
  signal.Notify(stop, os.Interrupt)
  
  //启动工作子进程
  go func() {
    for {
      log.Println("Worker: Doing some work")
      time.Sleep(time.Second * 1)
    }
  }()
  
  //等待收到关闭信号
  <-stop
  log.Println("Main: Got stop signal")
  
  //等待程序退出
  time.Sleep(time.Second * 1)
}

In this example, we create a channel called stop to respond to the shutdown signal, and Use os.Notify to subscribe to the os.Interrupt signal. The os.Interrupt signal is usually caused by the Ctrl C key. We also started a worker subprocess to simulate the job and output some messages on the console.

In the main function, we wait for the stop channel to receive data, that is, to receive the closing signal. When it happens, we print a log message and wait a second to allow the program to exit.

Graceful shutdown of the process

When we shut down the Golang process, there are some additional measures that can be taken to ensure that the process shuts down gracefully. These include closing other connections, waiting for running tasks to complete, saving data, etc. These measures help prevent data loss, file corruption, and other issues.

Here is an example that shows taking these extra steps when shutting down a process:

func main() {
  //创建关闭信号
  stop := make(chan os.Signal, 1)
  signal.Notify(stop, os.Interrupt, os.Kill)
  
  //创建TCP服务器
  listener, err := net.Listen("tcp", "localhost:8000")
  if err != nil {
    log.Fatal("Error:", err)
  }
  defer listener.Close()
  
  //启动RPC服务
  srv := rpc.NewServer()
  srv.Register(&MathService{})
  go srv.Accept(listener)
  
  //等待收到关闭信号
  <-stop
  log.Println("Main: Got stop signal")
  
  //关闭服务器
  log.Println("Main: Closing the server")
  listener.Close()
  
  //等待正在运行的任务完成
  log.Println("Main: Waiting for the tasks to finish")
  time.Sleep(time.Second * 3)
  
  //保存数据
  log.Println("Main: Saving the data")
  
  //等待程序退出
  time.Sleep(time.Second * 1)
}

In this example, we create a TCP server, RPC service, and shutdown signal. When we receive a shutdown signal, we shut down the server and wait for the running tasks to complete. Finally, we save the data to disk and wait for the program to exit.

Summary

In this article, we introduced how to use some tools and techniques in Golang to control the shutdown of the process. We learned how to use cancellation channels and signals to shut down processes. Additionally, we also discussed some techniques for gracefully shutting down processes, such as closing connections, waiting for tasks to complete, and saving data.

These tips can help us ensure the graceful shutdown of the process and avoid problems such as data loss and file corruption. Whether we are developing web servers, network applications, or other types of applications, process shutdown is very important.

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