How to correctly close threads in golang program

When writing Golang programs, it is very common to use concurrent programming. Golang's goroutine mechanism allows developers to easily create concurrent programs, but if goroutine is used improperly, it will cause problems such as memory leaks and resource waste in the program. Therefore, closing goroutine correctly is a necessary means to ensure program stability.

This article will discuss how to correctly close goroutine in Golang program.

Understanding goroutine

In Golang, goroutine is a lightweight thread. It runs on the operating system thread and can be scheduled on different threads at any time. Compared with traditional threads, goroutines are more lightweight and have less overhead to create and destroy.

In Golang, we can start a goroutine through the go keyword, for example:

go func() {
    // do something
}()

The life cycle of a goroutine started in this way is controlled by the Golang runtime system . When the goroutine's task is completed, the garbage collector will automatically reclaim the memory space it occupied.

Close goroutine immediately

Sometimes, we need to close goroutine immediately without waiting for it to complete, for example:

func task() {
    for {
        // do something
    }
}

func main() {
    go task()

    // do other things

    // 关闭task
    // ???
}

In the above code, we start A goroutine that performs tasks, but when the program needs to exit, we want to be able to close the goroutine immediately to avoid resource leaks.

Since Golang's goroutine does not provide a direct method to close it, we need to do some processing ourselves. A common approach is to use channels to control the shutdown of goroutines.

In the task function, we can receive a channel as a parameter and send a signal to the channel to indicate closing the goroutine. For example:

func task(quit chan bool) {
    for {
        select {
        case <- quit:
            return
        default:
            // do something
        }
    }
}

func main() {
    quit := make(chan bool)
    go task(quit)

    // do other things

    // 关闭task
    quit <- true
}

In the above code, we use the select mechanism in the task function to wait. When the closing signal of the quit channel is received, the function will exit immediately. In the main function, we create a quit channel and pass it as a parameter to the task function. When we need to close the goroutine, just send a true value to the quit channel.

gracefully shut down goroutine

In the actual development process, we not only need to ensure that the goroutine is shut down immediately, but also ensure that the goroutine can be shut down gracefully, that is, it can complete what is currently being executed before shutting down. Task. For example:

func task() {
    for {
        // do something
    }
}

func main() {
    quit := make(chan bool)
    go func() {
        for {
            select {
            case <- quit:
                // 执行清理操作
                // ...

                // 退出goroutine
                return
            default:
                // do something
            }
        }
    }()

    // do other things

    // 关闭task
    quit <- true
}

In the above code, we start a goroutine, which listens to the close signal of the quit channel through the select mechanism. When a close signal is received, it performs cleanup operations such as closing open files, closing database connections, etc. Finally, it exits the goroutine, ensuring that the goroutine shuts down gracefully.

sync.WaitGroup mechanism

In addition to using channels to control the closing of goroutines, Golang also provides the sync.WaitGroup mechanism to ensure the execution order and closing order of goroutines. For example:

func task(wg *sync.WaitGroup) {
    defer wg.Done()

    for {
        // do something
    }
}

func main() {
    var wg sync.WaitGroup

    wg.Add(1)
    go task(&wg)

    // do other things

    // 关闭task
    wg.Wait()
}

In the above code, we create a variable of type sync.WaitGroup and use the Add method to increase the goroutine counter. In the task function, we use the defer statement to ensure that the Done method is called after the task is completed, decrementing the counter value. Finally, use the Wait method in the main function to wait for all goroutines to complete their tasks.

Use the sync.WaitGroup mechanism to gracefully shut down goroutine, ensuring that all tasks can be completed before exiting.

Summary

In Golang programs, closing goroutine correctly is a necessary means to ensure program stability. Through the channel or sync.WaitGroup mechanism, we can control the closing order of goroutine to ensure that all tasks can be completed before exiting. When using goroutine, developers need to pay attention to issues such as memory leaks and resource waste to ensure the robustness and efficiency of the program.

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