Concepts and techniques of concurrent programming in Go language

With the continuous development of computer technology, multi-core CPUs have become standard. Concurrent programming is extremely important in today's software development, and Go language has become one of the most popular concurrent programming languages ​​due to its unique concurrency mechanism. In this article, we will discuss the concepts and techniques of concurrent programming in Go language.

1. The concept of concurrency

Concurrency means that two or more events occur within the same time interval. In computing, this means that multiple tasks can be executed simultaneously within the same time interval. Concurrent programming refers to the programming technology of writing programs that can perform multiple tasks at the same time.

The concepts of concurrent programming and parallel programming are different. Concurrent programming refers to performing multiple tasks simultaneously, while parallel programming refers to performing multiple tasks simultaneously on multiple processors or processing cores. In the computer field, concurrency and parallelism are often used interchangeably, but they are essentially different.

2. Concurrency in Go language

Go language supports concurrent programming in both syntax and runtime. Goroutine in Go language is an extremely lightweight thread. A Goroutine only needs to occupy a small amount of stack space to run. At the same time, a Go program can have thousands of Goroutines, which allows a Go program to Run concurrent tasks efficiently.

Concurrency in the Go language adopts the CSP concurrency model, which shares memory through communication rather than communicating through shared memory. In the Go language, we can use channels to implement communication between Goroutines.

You can define a channel in the following way:

ch := make(chan int)

Use the built-in go keyword of the Go language to start a Goroutine:

go printHelloWorld()

In this paragraph In the code, printHelloWorld() is a function. The Goroutine started through the go keyword will run independently in a new thread.

3. Techniques of Concurrent Programming

3.1 Use channel to coordinate Goroutine

As mentioned above, in Go language, we can use channel to implement Goroutine communication between. Channels can be used for coordination between two or more Goroutines and for control of shared resources.

package main

import "fmt"

func hello(done chan bool) {
    fmt.Println("Hello world Goroutine")
    done <- true
}

func main() {
    done := make(chan bool)
    go hello(done)
    <-done
    fmt.Println("main function")
}

In this code, we define a done channel outside the hello() function and pass it to hello() Function. In the hello() function, we print a message and write the true value into the done channel, representing hello() The function execution is completed. In the main() function, we read data from the channel through the <-done syntax, wait for the hello() function to complete and ## The #true value is written into the done channel. In this way, we achieve Goroutine coordination.

package main

import (
    "fmt"
    "time"
)

func main() {
    ch1 := make(chan int)
    ch2 := make(chan string)

    go func() {
        ch1 <- 1
    }()

    go func() {
        ch2 <- "hello"
    }()

    for i := 0; i < 2; i++ {
        select {
        case num := <-ch1:
            fmt.Println("ch1:", num)
        case str := <-ch2:
            fmt.Println("ch2:", str)
        case <-time.After(time.Millisecond * 100):
            fmt.Println("timeout")
        }
    }
}

ch1 and ch2, and start two Goroutines to write to these two channels respectively. Enter data. In the main() function, we process the input of these two channels through a for loop, and use the select statement to select one of the available channels and process its input. If no channel is available within a fixed period of time, we can use the time.After() function to implement timeout processing.

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