How to use golang channel

Golang channel is a very important feature in the Go language. In addition to handling concurrent programming tasks, it can also be used for message delivery and event notification. In actual applications, we usually use channels to enhance the robustness and scalability of the program. This article will focus on the basic use of Golang channel.

1. What is Golang channel?

In Golang, channel is a native type that can be used to transfer data between different goroutines. A channel can be viewed as a container that contains a certain number of elements, each element being of a type.

2. Definition and declaration of Golang channel

To define a channel, you can use the make method to specify the capacity and type of the channel:

ch := make(chan int, 10)

The above code creates a channel with a capacity of 10 int type channel.

3. Basic operations of Golang channel

1. Send data (data transfer)

We can use the channel operator<- to and from The channel writes data as follows:

ch <- 100

The above code is to write data 100 into channel ch.

2. Receive data (data reading)

Read data from the channel, and also use the channel operator <- to operate.

data := <- ch

The above code reads a data from ch and assigns it to the data variable.

3. Close channel

After using a channel, we need to close it to inform the receiver that it will not receive any more data.

close(ch)

4. The blocking characteristics of Golang channel

The channel in Golang has blocking characteristics, which helps us manage program resources, optimize performance and improve readability.

1. Blocking of unbuffered channels

In an unbuffered channel without any buffer, both the receiver and the sender will be blocked. In the following example, the unbuffered channel ch will block the execution of the main function until data is sent and received.

func main() {
    ch := make(chan int)
    go func() {
        fmt.Println("before data sent")
        ch <- 1
        fmt.Println("after data sent")
    }()
    fmt.Println("before data received")
    data := <-ch
    fmt.Println("data received:", data)
    fmt.Println("after data received")
}

In the above code, since the main goroutine executes to read the channel first, and the channel is blocked, it must wait until the data in goroutine ch <- 1 is sent .

2. Blocking of buffered channels

Compared with unbuffered channels, in buffered channels, the sender will not be blocked until a receiver receives data. Depending on the size of the buffer, a certain amount of data can be written to the channel without blocking.

In the following example, we create a buffered int type channel with a cache size of 2, but only send one data to it:

func main() {
    ch := make(chan int, 2)
    fmt.Println("buffered channel created")
    ch <- 1
    fmt.Println("data sent")
}

Since the channel's cache size is 2, Therefore, the send operation is not blocked when writing the first message to the channel. However, if we try to write a message again, it will block until there is space in the buffer.

3.select

The select statement can be used to process multiple channels and prevent blocking. It allows the program to choose between multiple channels, thereby achieving better concurrent processing and resource optimization. For any case, data can be received or sent, and the select statement is blocking.

In the following example, we use select to balance reads to two channels:

func main() {
    ch1 := make(chan int)
    ch2 := make(chan int)
    go func() {
        time.Sleep(time.Second)
        ch1 <- 1
    }()
    go func() {
        time.Sleep(2 * time.Second)
        ch2 <- 2
    }()
    for i := 0; i < 2; i++ {
        select {
        case data1 := <-ch1:
            fmt.Println("data from ch1:", data1)
        case data2 := <-ch2:
            fmt.Println("data from ch2:", data2)
        }
    }
}

In the above example, the select syntax allows us to slave from the obedient channel ch1 Switch to ch2 until we successfully get data from one of the channels. After this, the program will exit.

Summary:

This article introduces channels in Go language in detail, and describes the specific usage and importance of Golang channels. When we deal with concurrent programming problems, channel is often our first choice of data structure. In Golang, channels have many advantages, such as cross-program communication, synchronization and blocking mechanisms, and selectors, etc., which can enable the Go language to be effectively applied and perform efficiently in many aspects. I hope this article can help you better use channels in the Go language and provide assistance in developing efficient Go language programs.

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