golang closes Ctrip

In recent years, Go language has become a very popular programming language in the field of high concurrency and large-scale data applications. Among them, in the Go language, coroutines (also called Go routines) are a very important concept, which are very helpful for concurrent programming.

Coroutines can be regarded as lightweight threads. They do not require kernel-level thread scheduling by the operating system, but are scheduled by the runtime environment of the Go language. Therefore, the creation and destruction of coroutines are relatively fast and can support very efficient concurrent processing.

However, in actual applications, we often need to close running coroutines, which will involve some problems. This article will analyze these problems in detail.

The problem of closing a coroutine

It is not simple to close a coroutine. This is because, in the Go language, coroutines are scheduled by the runtime environment of the Go language, and their execution order and running status are determined by the runtime environment itself. If you want to shut down a coroutine, it is difficult to directly stop its execution through external forces.

The runtime environment of Go language provides the runtime.Goexit() function to stop the execution of the current coroutine, but it can only stop the current coroutine and cannot stop other coroutines.

So, how do we close a running coroutine? At this time, we need to consider the following issues:

1. How to notify the coroutine to stop itself

In some cases, we can A flag is set in the coroutine to indicate whether it needs to stop, and then under certain conditions, we can notify the coroutine to stop itself by setting this flag.

However, this method only works for those coroutines that can self-stop. For those coroutines that cannot stop themselves, we need to use other methods to close them.

2. How to wait for the coroutine to complete

If we cannot stop a coroutine by ourselves, then we need to wait for it to complete its work before closing it. At this time, we need a reliable way to wait for the coroutine to complete.

In the Go language, we can wait for the completion of the coroutine by using WaitGroup. WaitGroup is a concurrency primitive in the Go language, which can be used to wait for the completion of a group of coroutines.

3. How to close safely

When closing the coroutine, we need to ensure the safety of the shutdown. This is because if the coroutine is not completely cleaned up before closing, it may cause memory leaks or other undesirable consequences.

In the Go language, we can use the defer statement to perform cleanup work and ensure that the coroutine completes all necessary cleanup work before closing.

Implementation of closing coroutines in Go language

After understanding the problem of closing coroutines, let’s take a look at how to close coroutines in Go language. Here are some methods:

Method 1: Use signal notification

In Go language, we can use channel to achieve communication between coroutines. We can make a coroutine stop itself by sending a signal to a specific channel.

The following is a sample code:

package main

import (
    "fmt"
    "time"
)

func worker(done chan bool) {
    fmt.Println("Worker: started")
    time.Sleep(time.Second)
    fmt.Println("Worker: done")
    done <- true
}

func main() {
    done := make(chan bool, 1)
    go worker(done)

    <-done
    fmt.Println("Main: done")
}

In the above sample code, we first define a coroutine named worker, which will do some work and Send a signal to the done channel when completed. In the main function, we create a channel named done and pass it to the coroutine.

While waiting for the done channel, the main function will be blocked until the worker coroutine completes and sends a signal. Once the signal is received, the main function will continue to execute and output Main: done.

Method 2: Use context.Context

In Go language, we can use the context package to manage the context of the coroutine. By using context.Context, we can start a coroutine in a specified context and cancel the context when we need to stop the coroutine, thereby stopping the execution of the coroutine.

The following is a sample code:

package main

import (
    "fmt"
    "time"
    "context"
)

func worker(ctx context.Context) {
    fmt.Println("Worker: started")
    for {
        select {
        case <-ctx.Done():
            fmt.Println("Worker: done")
            return
        default:
            fmt.Println("Worker: working")
            time.Sleep(time.Second)
        }
    }
}

func main() {
    ctx, cancel := context.WithCancel(context.Background())
    go worker(ctx)

    time.Sleep(3 * time.Second)
    cancel()

    fmt.Println("Main: done")
}

In the above sample code, we first define a coroutine named worker, in its main loop We use the select statement to listen to two channels: the ctx.Done() and default channels. If the ctx.Done() channel receives a signal, the coroutine will exit.

In the main function, we first create a context.Context and add it to a context using the context.WithCancel function . Then, we pass this context to the workercoroutine. After executing for a period of time, we call the cancel function to cancel the context, thereby stopping the execution of the worker coroutine.

Summary

Through the above two methods, we can safely close the coroutine in Go language. When closing the coroutine, we need to consider whether the coroutine can stop itself, how to wait for the coroutine to complete, and how to safely close the coroutine. By properly using the concurrency primitives of the Go language such as channel, WaitGroup, and context, we can achieve efficient, safe, and reliable coroutine shutdown operations.

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