Analyze the single-threaded characteristics of Go language

Analysis of single-threaded features of Go language

In Go language, although we can use goroutine to achieve concurrency, in actual execution, the Go program is still single-threaded In progress. This seemingly contradictory phenomenon is mainly due to the built-in scheduler of the Go language. This article will provide an in-depth analysis of the single-threaded features of the Go language and illustrate its working principle through specific code examples.

1. Goroutine and single thread

In the Go language, we can create goroutine through the keyword go, which allows us to easily perform concurrent programming. But it should be noted that although goroutine can allow multiple tasks to be executed simultaneously, these tasks actually run on a single thread. The design concept of Go language is to be concise and clear in programming, hiding the underlying thread management, so that developers do not need to pay too much attention to thread management and synchronization, and focus more on the implementation of business logic.

2. The role of the scheduler

The Go language scheduler is responsible for controlling the scheduling and execution of goroutines. It will allocate multiple goroutines to available logical processors for execution. One logical processor corresponds to one operating system thread, which means that the Go program still runs in a single thread under the hood. The scheduler switches goroutines between different logical processors to achieve the effect of concurrent execution.

3. Sample code analysis

Next, we use a specific code example to analyze the single-threaded characteristics of the Go language. Suppose we have a simple program that contains a main goroutine and two sub-goroutines, and each goroutine will print a piece of text:

package main

import (
    "fmt"
    "time"
)

func printText(text string) {
    for i := 0; i < 5; i {
        fmt.Println(text)
        time.Sleep(100 * time.Millisecond)
    }
}

func main() {
    go printText("Goroutine 1")
    go printText("Goroutine 2")

    printText("Main goroutine")

    time.Sleep(2 * time.Second)
}

In the above code, we created a printText function to print text, and started three goroutines in the main function to print different Text. Prevent the program from exiting prematurely by calling time.Sleep.

4. Execution process analysis

When we run this code, the output will be similar to the following:

Main goroutine
Goroutine 1
Goroutine 1
Goroutine 2
Goroutine 1
Goroutine 2
Goroutine 1
Goroutine 2
Goroutine 1
Goroutine 2
Goroutine 1

It can be seen from the output that although we have started multiple goroutines, they are still executed alternately in a single thread, and printText## in the main function #The call also participates in the scheduling process of the scheduler.

Reference materials

• Go language official documentation: https://golang.org/doc/
• "Go Language Practical Combat": Written by Xu Shiwei

【over】

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