Comparative analysis of coroutines and threads in Go language

Go language Goroutine and Thread are two common concepts in concurrent programming. They can both be used to handle concurrent tasks, but they have different implementation and scheduling methods. , resource consumption and other aspects are significantly different. This article will deeply explore the similarities and differences between Go language coroutines and threads, and deepen understanding through specific code examples.

1. Coroutines vs threads

1.1 Implementation method

The coroutines of the Go language are lightweight threads managed by the Go language runtime (Goruntime). Language keyword go to create. Coroutines have their own stack space, but they share the address space of the same thread. This design makes the creation and destruction of coroutines less expensive and can efficiently perform large-scale concurrent processing.

Threads are the basic unit of operating system scheduling. Each thread has an independent execution context and stack. Switching between threads requires the intervention of the operating system. In contrast, thread creation and destruction are expensive, so the number of threads needs to be carefully managed.

1.2 Scheduling method

The coroutines of the Go language are scheduled by the Go language runtime. It adopts the M:N scheduling model, that is, the scheduling of M coroutines is mapped to N Executed on a system thread. This method can achieve concurrent processing without increasing the number of system threads, improving efficiency.

The operating system is responsible for thread scheduling. The operating system determines the execution order of threads based on the priority of the thread and the scheduling algorithm. Thread scheduling is implemented by the operating system kernel, so it may involve switching between user mode and kernel mode, which will bring certain performance overhead.

1.3 Resource consumption

Since coroutines are lightweight threads, their resource consumption is much smaller than that of threads. The stack space of the coroutine can be specified in size when created and can be dynamically adjusted to avoid stack overflow problems. In contrast, the stack space of threads is large and fixed, which easily leads to waste of resources.

2. Specific code examples

The following is a simple Go language coroutine code example:

package main

import (
    "fmt"
    "time"
)

func main() {
    for i := 0; i < 5; i++ {
        go func(n int) {
            fmt.Println("Goroutine", n)
        }(i)
    }

    time.Sleep(time.Second) // 等待所有协程执行完毕
}

In this example, we pass go func( ) creates 5 coroutines and prints the corresponding number in each coroutine. In the main thread, wait for all coroutines to finish executing through time.Sleep.

The following is a C example using threads:

#include <iostream>
#include <thread>

void printThread(int n) {
    std::cout << "Thread " << n << std::endl;
}

int main() {
    for (int i = 0; i < 5; i++) {
        std::thread t(printThread, i);
        t.join();
    }

    return 0;
}

In this example, we create 5 threads through std::thread, and in each Print the corresponding number in the thread. Use join in the main thread to wait for all threads to complete execution.

3. Summary

Go language coroutines and threads have different characteristics and advantages in concurrent programming. The lightweight design of coroutines makes it more suitable for handling large-scale concurrent tasks, while the implementation of threads is limited by the operating system's scheduling algorithm, which may result in greater resource consumption.

Through the introduction and code examples of this article, I believe that readers will have a deeper understanding of the similarities and differences between Go language coroutines and threads, and hope that they can choose appropriate methods to improve program performance in actual concurrent programming. and efficiency.

The above is the detailed content of Comparative analysis of coroutines and threads in Go language. For more information, please follow other related articles on the PHP Chinese website!