How to stay connected in golang

In recent years, due to the gradual increase in application scenarios such as distributed servers and big data processing, Golang (Go language) has gradually become a popular programming language. With its efficient concurrency processing capabilities and easy-to-learn syntax, Golang is widely used in developing high-performance, high-concurrency applications. Among them, long connection is a common communication method. In this article, we will explore how to use Golang to implement long connection technology.

1. What is a long connection?

Before understanding long connections, we need to understand short connections first. Short connection is a connection mode between the client and the server. The client will disconnect after completing the communication with the server. The advantage of this method is that it can control the load cost of the server, but in some scenarios it is necessary to keep the connection constant, such as audio streaming, video streaming and other scenarios with large data traffic.

Long connection means that after the connection is established, the client and the server remain connected without disconnecting. In this case, the server can respond to the client's request in real time without re-establishing the connection. This method has the following advantages:

1. High data transmission efficiency: long connections do not need to perform multiple handshakes and waves after establishment, and data can be transmitted more efficiently.
2. Low memory consumption: short connections require frequent establishment and disconnection, and each connection establishment requires system memory occupation, while long connections can avoid this occupation.
3. High stability: Due to the persistence of long connections, they will be more stable than short connections.

2. Implementation method of long connection in Golang

It is also very simple to implement long connection in Golang. We can implement this technology through TCP sockets and Goroutine control.

1. Achieving long connections through TCP sockets

In Golang, it is very common to use TCP sockets to implement network connections. The following is a TCP socket long connection sample code:

// 建立tcp连接
conn, err := net.DialTimeout("tcp", "localhost:9000", time.Second*time.Duration(5))
if err != nil {
    fmt.Println("dial error!", err)
    return
}

//进行读写操作，长时间不操作会断开链接
for {
    _, err := conn.Write([]byte("hello"))
    if err != nil {
        fmt.Println("write err", err)
        return
    }

    time.Sleep(time.Millisecond * time.Duration(500))
}

In the code, we establish a TCP connection through the net.DialTimeout() method, and forPerform reading and writing operations in the loop. At the same time, we use the time.Sleep() function to poll regularly to maintain the server's response to the client.

2. Achieving long connections through Goroutine

Another way to implement long connections is to use Goroutine technology. Goroutine is a unique lightweight thread in Golang. It can start multiple lightweight threads at the same time to achieve high concurrency and efficient communication processing. The following is a sample code that uses Goroutine to implement long connections:

// 建立tcp连接
conn, err := net.DialTimeout("tcp", "localhost:9000", time.Second*time.Duration(5))
if err != nil {
    fmt.Println("dial error!", err)
    return
}

//开一个协程并发读取数据
go func() {
    for {
        _, err = ioutil.ReadAll(conn)
        if err != nil {
            fmt.Println("read err", err)
            return
        }
    }
}()

//开一个协程并发写入数据
go func() {
    for {
        _, err := conn.Write([]byte("hello"))
        if err != nil {
            fmt.Println("write err", err)
            return
        }

        time.Sleep(time.Millisecond * time.Duration(500))
    }
}()

//阻塞主线程，避免程序运行结束
select {}

In the code, we first use the net.DialTimeout() method to establish a TCP connection, and then use two Goroutine coroutines Perform read and write operations. Goroutine is a thread running on the main thread. We do not use the for loop scheduled polling method, but start two Goroutine coroutines to read and write data. In Golang, Goroutine's concurrent processing capabilities are very outstanding and have relatively high processing efficiency.

3. Precautions for long connections

In the process of using long connection technology, you also need to pay attention to the following points:

1. Because long connections are on the client side The connection is always maintained with the server, so if there is a long-term connection, the server may connect too many clients, resulting in excessive CPU processing power.
2. When using long connections, the server's load balancing capabilities should be enhanced. If a server encounters too many connection requests, it should be automatically allocated to other servers to ensure the normal operation of the server.
3. Since long connections need to be continuously active, the bottom layer needs to be designed with time wheels, etc. Therefore, during development, you should try to avoid mistakenly implementing the "ping-pong" monitoring mechanism that consumes too much performance.

4. Summary

Long connection is a very efficient communication method, which is very commonly used when processing large amounts of data such as data stream transmission. In Golang, it is also very simple to implement long connections, which can be achieved through TCP sockets or Goroutine technology. Of course, when using long connections, we also need to pay attention to some issues such as security and load balancing. These require us to continuously summarize and accumulate experience during the specific development process to achieve more efficient and stable applications.

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