Linux下C++多线程同步怎么做

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

std::mutex mtx; // 全局互斥锁

void print_block(int n, char c) {
    mtx.lock(); // 加锁
    for (int i = 0; i < n; ++i) {
        std::cout << c;
    }
    mtx.unlock(); // 解锁
}

int main() {
    std::thread th1(print_block, 50, '*');
    std::thread th2(print_block, 50, '$');

    th1.join();
    th2.join();

    return 0;
}

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

std::mutex mtx;
std::condition_variable cv;
bool ready = false;

void print_id(int id) {
    std::unique_lock<std::mutex> lck(mtx);
    cv.wait(lck, []{return ready;}); // 等待条件满足
    std::cout << "thread " << id << std::endl;
}

void go() {
    std::lock_guard<std::mutex> lck(mtx);
    ready = true;
    cv.notify_all(); // 通知所有等待线程
}

int main() {
    std::thread threads[10];
    for (int i = 0; i < 10; ++i) {
        threads[i] = std::thread(print_id, i);
    }
    go();
    for (auto& th : threads) {
        th.join();
    }
    return 0;
}

#include <iostream>
#include <thread>
#include <semaphore>

std::binary_semaphore sem(0); // 二进制信号量

void print_block(int n, char c) {
    sem.acquire(); // 等待信号量
    for (int i = 0; i < n; ++i) {
        std::cout << c;
    }
}

void go() {
    std::this_thread::sleep_for(std::chrono::seconds(1)); // 模拟任务
    sem.release(); // 释放信号量
}

int main() {
    std::thread th1(print_block, 50, '*');
    std::thread th2(print_block, 50, '$');
    std::thread t(go);

    th1.join();
    th2.join();
    t.join();

    return 0;
}

#include <iostream>
#include <thread>
#include <atomic>

std::atomic<int> counter(0);

void increment() {
    for (int i = 0; i < 100000; ++i) {
        ++counter;
    }
}

int main() {
    std::thread t1(increment);
    std::thread t2(increment);

    t1.join();
    t2.join();

    std::cout << counter << std::endl;
    return 0;
}

#include <iostream>
#include <thread>
#include <barrier>

std::barrier bar(2); // 创建一个屏障，等待两个线程

void print_hello() {
    std::cout << "Hello ";
    bar.wait(); // 等待屏障
    std::cout << "World!" << std::endl;
}

int main() {
    std::thread t1(print_hello);
    std::thread t2(print_hello);

    t1.join();
    t2.join();

    return 0;
}