C++并发编程有哪些实践案例

C++并发编程的实践案例有很多，以下是一些常见的例子：

1. 多线程计数器：这是一个简单的多线程计数器示例，使用C++11的std::thread和std::atomic实现。

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

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

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

int main() {
    std::vector<std::thread> threads;
    for (int i = 0; i < 10; ++i) {
        threads.emplace_back(increment);
    }

    for (auto& t : threads) {
        t.join();
    }

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

2.生产者消费者模型：这是一个使用std::queue、std::mutex和std::condition_variable实现的生产者消费者模型示例。

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

std::queue<int> dataQueue;
std::mutex mtx;
std::condition_variable cv;

void producer() {
    for (int i = 0; i < 10; ++i) {
        std::unique_lock<std::mutex> lock(mtx);
        dataQueue.push(i);
        cv.notify_one();
    }
}

void consumer() {
    while (true) {
        std::unique_lock<std::mutex> lock(mtx);
        cv.wait(lock, [] { return !dataQueue.empty(); });
        int value = dataQueue.front();
        dataQueue.pop();
        std::cout << "Consumed: " << value << std::endl;
    }
}

int main() {
    std::thread producerThread(producer);
    std::thread consumerThread(consumer);

    producerThread.join();
    consumerThread.join();

    return 0;
}

3. 线程池：这是一个使用std::thread、std::queue、std::mutex和std::condition_variable实现的简单线程池示例。

#include <iostream>
#include <thread>
#include <queue>
#include <mutex>
#include <condition_variable>
#include <vector>
#include <functional>

class ThreadPool {
public:
    ThreadPool(size_t numThreads) : stop(false) {
        for (size_t i = 0; i < numThreads; ++i) {
            workers.emplace_back([this] {
                while (true) {
                    std::function<void()> task;
                    {
                        std::unique_lock<std::mutex> lock(this->mtx);
                        this->cond.wait(lock, [this] { return this->stop || !this->tasks.empty(); });
                        if (this->stop && this->tasks.empty()) {
                            return;
                        }
                        task = std::move(this->tasks.front());
                        this->tasks.pop();
                    }
                    task();
                }
            });
        }
    }

    ~ThreadPool() {
        {
            std::unique_lock<std::mutex> lock(mtx);
            stop = true;
        }
        cond.notify_all();
        for (auto& worker : workers) {
            worker.join();
        }
    }

    template <typename F, typename... Args>
    void enqueue(F&& f, Args&&... args) {
        {
            std::unique_lock<std::mutex> lock(mtx);
            tasks.emplace([f, args...] { f(args...); });
        }
        cond.notify_one();
    }

private:
    std::vector<std::thread> workers;
    std::queue<std::function<void()>> tasks;
    std::mutex mtx;
    std::condition_variable cond;
    bool stop;
};

void task(int id) {
    std::cout << "Task " << id << " is running on thread " << std::this_thread::get_id() << std::endl;
}

int main() {
    ThreadPool pool(4);
    for (int i = 0; i < 10; ++i) {
        pool.enqueue(task, i);
    }

    std::this_thread::sleep_for(std::chrono::seconds(1));
    return 0;
}

这些示例展示了C++并发编程的一些基本概念和实践方法。在实际项目中，你可能需要根据具体需求选择合适的并发编程技术和工具。