How to debug coroutine program in golang? Sharing common tips

In the Go language, Goroutine is a very commonly used feature. Coroutines are lightweight threads that can be executed in parallel with other coroutines, but they are not controlled by operating system scheduling, but are scheduled by the Go runtime. The scheduler switches between multiple coroutines and lets them execute alternately to take full advantage of multi-core CPUs, thereby improving program concurrency and efficiency.

However, sometimes we need to debug and troubleshoot coroutines. For example, we want to know how many coroutines are running in the current program, which coroutines are blocked, which coroutines have exceptions, etc. This article will introduce some common debugging techniques to help Go developers better debug coroutine programs.

1. Get the number of coroutines

We can use the NumGoroutine() function provided by the built-in runtime package to get the current The number of coroutines in the process. This function returns an integer representing the number of coroutines running in the current process. We can call this function anywhere in the code as follows:

import "runtime"

// 获取当前进程中协程的数量
num := runtime.NumGoroutine()

2. Get the coroutine ID

We can create it using the go statement coroutine and save it in a variable. This variable is actually the ID of a coroutine, and we can use it to get the status of the coroutine. The following is a simple example:

import (
    "fmt"
    "runtime"
)

func worker() {
    fmt.Println("协程正在运行")
}

func main() {
    // 创建一个新的协程，并保存它的 ID
    goID := go worker()

    // 输出协程的 ID
    fmt.Printf("协程的 ID 是：%d\n", goID)

    // 获取当前进程中协程的数量
    num := runtime.NumGoroutine()
    fmt.Printf("当前进程中协程的数量是：%d\n", num)
}

3. Get the coroutine status

We can use the Gosched( provided by the built-in runtime package ) and Goexit() functions to control and obtain the status of the coroutine. Gosched()The function will suspend the execution of the current coroutine and give up the CPU to other coroutines; Goexit()The function will end the execution of the current coroutine and give up the CPU to Other coroutines are executed. We can use these two functions in the code to control the execution of the coroutine.

Here is a simple example showing how to use the Gosched() and Goexit() functions:

import (
    "fmt"
    "runtime"
)

func worker() {
    for i := 0; i < 5; i++ {
        fmt.Println("协程正在工作", i)
        // 调用 Gosched() 函数，暂停当前协程的执行，让出 CPU
        runtime.Gosched()
    }
    // 调用 Goexit() 函数，结束当前协程的执行
    runtime.Goexit()
}

func main() {
    // 创建一个新的协程
    go worker()

    // 获取当前进程中协程的数量
    num := runtime.NumGoroutine()
    fmt.Printf("当前进程中协程的数量是：%d\n", num)

    // 等待协程结束
    runtime.Gosched()

    // 获取当前进程中协程的数量
    num = runtime.NumGoroutine()
    fmt.Printf("当前进程中协程的数量是：%d\n", num)
}

4. Manual settings Scheduling of coroutines

In the Go language, we can control the scheduling of coroutines by setting the value of the runtime.GOMAXPROCS() function. The parameter of this function specifies the number of coroutines executed at the same time. If it is set to 1, then all coroutines will be executed in the same thread; if it is set to a number greater than 1, multiple threads will be created to execute the coroutines. . We can manually set this parameter to control the concurrency and efficiency of the coroutine.

The following is a simple example showing how to use the GOMAXPROCS() function to set the concurrency of the coroutine:

import (
    "os"
    "runtime"
)

func main() {
    // 获取 CPU 的数目
    numCPUs := os.NumCPU()
    // 设置 GOMAXPROCS 的值
    runtime.GOMAXPROCS(numCPUs)
    // ...
}

Summary

In In this article, we introduce some common debugging techniques to help Go developers better debug coroutine programs. We learned how to get the number of coroutines, get the coroutine ID, get the coroutine status, and manually set the schedule of the coroutine. These techniques can help us better understand the working principle of coroutines, master the skills of using coroutines, and improve the concurrency and efficiency of the program.

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