C++如何在多线程中管理共享内存

#include <thread>
#include <mutex>
#include <vector>

std::vector<int> shared_data;
std::mutex data_mutex;

void add_data(int value) {
    std::lock_guard<std::mutex> lock(data_mutex);
    shared_data.push_back(value);
}

int main() {
    std::thread t1(add_data, 1);
    std::thread t2(add_data, 2);
    t1.join();
    t2.join();
    return 0;
}

#include <atomic>
#include <thread>

std::atomic<int> counter{0};

void increment() {
    for (int i = 0; i < 1000; ++i) {
        counter.fetch_add(1);
    }
}

int main() {
    std::thread t1(increment);
    std::thread t2(increment);
    t1.join();
    t2.join();
    // counter 正确等于 2000
    return 0;
}

#include <queue>
#include <condition_variable>

std::queue<int> message_queue;
std::mutex queue_mutex;
std::condition_variable cv;
bool finished = false;

void consumer() {
    while (true) {
        std::unique_lock<std::mutex> lock(queue_mutex);
        cv.wait(lock, [] { return !message_queue.empty() || finished; });

        if (finished && message_queue.empty()) break;

        int msg = message_queue.front();
        message_queue.pop();
        lock.unlock();

        // 处理消息
        printf("Consumed: %d\n", msg);
    }
}

void producer() {
    for (int i = 1; i <= 5; ++i) {
        {
            std::lock_guard<std::mutex> lock(queue_mutex);
            message_queue.push(i);
        }
        cv.notify_one();
    }
    {
        std::lock_guard<std::mutex> lock(queue_mutex);
        finished = true;
    }
    cv.notify_one();
}

thread_local int thread_id = 0;

void set_id(int id) {
    thread_id = id;
    printf("Thread %d running\n", thread_id);
}