Golang coroutine analysis: What secrets are hidden behind it?

Golang coroutine analysis: What kind of mystery is hidden behind it, specific code examples are needed

In the Go language, Goroutine is one of its concurrency models Very important concept. A coroutine is a lightweight thread that is scheduled by the runtime system of the Go language and can execute multiple coroutines concurrently on a single thread. Through coroutines, we can achieve efficient concurrent programming and improve program performance and response speed. So, what is the secret hidden behind Golang coroutines? Next we will delve deeper into this issue and give specific code examples to explain.

Creation and startup of coroutines

In the Go language, creating a coroutine is very simple. You only need to add the keyword "go" in front of the function or method call to start one. Coroutines. For example:

package main

import (
    "fmt"
)

func main() {
    go sayHello()
    fmt.Println("Main goroutine")
}

func sayHello() {
    fmt.Println("Hello from Goroutine")
}

In the above code, we start a new coroutine by go sayHello(), which will execute sayHello() function and prints "Hello from Goroutine". In the main() function, we print "Main goroutine". The two pieces of information may be output staggered because coroutines are executed concurrently and there is no fixed execution order.

Scheduling of coroutines

The runtime system of the Go language is responsible for the scheduling and management of coroutines to ensure that multiple coroutines can be executed concurrently on a single thread. In the Go language, there is a model called "GMP", namely Goroutine, M (Machine, operating system thread) and P (Processor, logical processor). Through this model, the Go language achieves efficient concurrent execution of coroutines.

package main

import (
    "fmt"
    "sync"
)

func main() {
    var wg sync.WaitGroup
    wg.Add(2)

    go func() {
        defer wg.Done()
        fmt.Println("Goroutine 1")
    }()

    go func() {
        defer wg.Done()
        fmt.Println("Goroutine 2")
    }()

    wg.Wait()
}

In the above code, we use sync.WaitGroup to wait for all coroutines to complete execution. Use wg.Add(2) and wg.Done() to increase and decrease the number of waiting coroutines respectively. We created two anonymous functions as coroutines that print "Goroutine 1" and "Goroutine 2" respectively. In the main() function, wait for the completion of the execution of these two coroutines through wg.Wait().

Communication between coroutines

In actual concurrent programming, data exchange and sharing of data are usually required between coroutines. Go language provides channel to realize communication between coroutines. channel is a type-safe communication mechanism that can ensure the security of concurrent access. Here is a simple example:

package main

import (
    "fmt"
)

func main() {
    ch := make(chan int)

    go func() {
        ch <- 42
    }()

    result := <-ch
    fmt.Println(result)
}

In the above code, we create a channel and send the integer 42 to the channel in a coroutine. In the main() function, data is received from channel through the operator and printed out.

The Mystery of Coroutines

There are many mysteries hidden behind coroutines, the most important of which is that it can avoid expensive thread creation and switching overhead, thereby achieving more efficient concurrent programming. Since coroutines are scheduled by user mode in the runtime system of Go language and do not require the participation of operating system threads, the overhead of creating and switching coroutines is very small. This allows us to easily create a large number of coroutines to handle concurrent tasks without worrying about performance issues.

Summary

Through the introduction of this article, we have deeply explored the mysteries of Golang coroutines and given specific code examples to explain the creation, scheduling and communication of coroutines. Coroutines are a very powerful concurrent programming tool in the Go language. By making full use of coroutines, we can achieve efficient concurrent programming and improve program performance and response speed. I hope the content of this article can help readers better understand and apply the relevant knowledge of Golang coroutines.

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