C++ 多线程互斥锁(mutex，lock，lock_guard)

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[TOC]

源代码

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#include <iostream>
#include <thread>

void work1(int& sum) {
    for (int i = 1; i < 5000; i++) {
        sum += i;
    }
}

void work2(int& sum) {
    for (int i = 5000; i <= 10000; i++) {
        sum += i;
    }
}

int fun() {
    int sum = 0;
    for (int i = 1; i <= 10000; i++) {
        sum += i;
    }
    return sum;
}

int main()
{
    int ans = 0;
    std::thread t1(work1, std::ref(ans));
    std::thread t2(work2, std::ref(ans));
    t1.join();
    t2.join();
    std::cout << "sum1 : " << ans << std::endl;
    std::cout << "sum2 : " << fun() << std::endl;
    return 0;
}

第一实现 mutex参数lock， unlock

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#include <iostream>
#include <thread>
#include <mutex>

void work1(int& sum, std::mutex& mylock) {
    for (int i = 1; i < 5000; i++) {
        mylock.lock();
        sum += i;
        mylock.unlock();
    }
}

void work2(int& sum, std::mutex& mylock) {
    for (int i = 5000; i <= 10000; i++) {
        mylock.lock();
        sum += i;
        mylock.unlock();
    }
}

int fun() {
    int sum = 0;
    for (int i = 1; i <= 10000; i++) {
        sum += i;
    }
    return sum;
}

int main()
{
    std::mutex mylock;
    int ans = 0;
    std::thread t1(work1, std::ref(ans), std::ref(mylock));
    std::thread t2(work2, std::ref(ans), std::ref(mylock));
    t1.join();
    t2.join();
    std::cout << "sum1 : " << ans << std::endl;
    std::cout << "sum2 : " << fun() << std::endl;
    return 0;
}

第二种 lock_guard类模板

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#include <iostream>
#include <thread>
#include <mutex>

void work1(int& sum, std::mutex& mylock) {
    for (int i = 1; i < 5000; i++) {
        std::lock_guard<std::mutex> mylock_guard(mylock);
        sum += i;
    }
}

void work2(int& sum, std::mutex& mylock) {
    for (int i = 5000; i <= 10000; i++) {
        std::lock_guard<std::mutex> mylock_guard(mylock);
        sum += i;
    }
}

int fun() {
    int sum = 0;
    for (int i = 1; i <= 10000; i++) {
        sum += i;
    }
    return sum;
}

int main()
{
    std::mutex mylock;
    int ans = 0;
    std::thread t1(work1, std::ref(ans), std::ref(mylock));
    std::thread t2(work2, std::ref(ans), std::ref(mylock));
    t1.join();
    t2.join();
    std::cout << "sum1 : " << ans << std::endl;
    std::cout << "sum2 : " << fun() << std::endl;
    return 0;
}

https://cloud.tencent.com/developer/article/1583894

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