Execution timing of golang functions and goroutine

In the Go language, functions called synchronously are executed sequentially in the current goroutine, while functions called asynchronously are executed in parallel in the new goroutine through the go keyword. By controlling how functions are called, you can customize program concurrency behavior and optimize its performance.

Execution timing of functions and Goroutines in Go language

Understand the concurrency model of Go language

The Go language adopts the Communicating Sequential Process (CSP) model and provides goroutine and channel to implement concurrent programming. Goroutines are lightweight execution threads, similar to threads in other languages, but more efficient from a scheduling and resource allocation perspective.

The execution timing of functions and Goroutines

The execution timing of functions and goroutines in the Go language depends on how they are called and where they are called.

• Synchronous call: When a function is called synchronously (for example, directly called in the main goroutine), it will be executed sequentially in the current goroutine.
• Asynchronous call: When a function is called asynchronously (for example, in a goroutine through the go keyword), it will be executed in parallel in a new goroutine . The execution timing of this goroutine is determined by the scheduler, and it can be executed immediately or at a later time.

Practical case

The following is a simple example comparing the impact of synchronous calls and asynchronous calls:

package main

import (
    "fmt"
    "time"
)

func main() {
    // 同步调用
    start := time.Now()
    fmt.Println("同步调用开始")
    syncFunction()
    fmt.Println("同步调用结束", time.Since(start))

    // 异步调用
    start = time.Now()
    fmt.Println("异步调用开始")
    go asyncFunction()
    fmt.Println("异步调用结束", time.Since(start))
}

func syncFunction() {
    for i := 0; i < 100000000; i++ {
        // noop
    }
}

func asyncFunction() {
    for i := 0; i < 100000000; i++ {
        // noop
    }
}

In synchronous calls,syncFunction is executed sequentially in the current goroutine, causing the program to run for about 2 seconds in total. In an asynchronous call, asyncFunction is executed in parallel in a new goroutine, resulting in a total program running time of less than 1 second because the main function completes before asyncFunction Just continue to execute.

Conclusion

Understanding the execution timing of functions and goroutines is crucial to effectively using concurrency in the Go language. By controlling how functions are called, you can tailor your program's concurrency behavior and optimize its performance.

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