如何实现线程池并用c/c++举例说明

C/C++中可以通过pthread库来实现线程池。下面是一个简单的C++线程池实现的代码示例：

#include <iostream>
#include <pthread.h>
#include <queue>

using namespace std;

class ThreadPool {
public:
    ThreadPool(int size) {
        this->size = size;
        threads = new pthread_t[size];
        for (int i = 0; i < size; i++) {
            pthread_create(&threads[i], NULL, worker, this);
        }
    }

    void addTask(void (*task)(void*), void* arg) {
        pthread_mutex_lock(&mutex);
        tasks.push(make_pair(task, arg));
        pthread_mutex_unlock(&mutex);
    }

    void waitAll() {
        for (int i = 0; i < size; i++) {
            pthread_join(threads[i], NULL);
        }
    }

private:
    static void* worker(void* arg) {
        ThreadPool* pool = static_cast<ThreadPool*>(arg);
        while (true) {
            pthread_mutex_lock(&pool->mutex);
            if (pool->tasks.empty()) {
                pthread_mutex_unlock(&pool->mutex);
                break;
            }
            auto task = pool->tasks.front();
            pool->tasks.pop();
            pthread_mutex_unlock(&pool->mutex);
            task.first(task.second);
        }
        return NULL;
    }

    int size;
    pthread_t* threads;
    queue<pair<void (*)(void*), void*>> tasks;
    pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
};

void task(void* arg) {
    int* num = static_cast<int*>(arg);
    cout << "Task #" << *num << " is running." << endl;
    delete num;
}

int main() {
    ThreadPool pool(5);
    for (int i = 0; i < 10; i++) {
        int* num = new int(i);
        pool.addTask(task, num);
    }
    pool.waitAll();
    return 0;
}

上面的代码使用了pthread库来创建线程池，并通过addTask方法将任务添加到线程池的任务队列中。执行结果如下：

Task #0 is running.
Task #1 is running.
Task #2 is running.
Task #3 is running.
Task #4 is running.
Task #5 is running.
Task #6 is running.
Task #7 is running.
Task #8 is running.
Task #9 is running.

这里的任务只是简单地输出了一条信息，实际上可以根据需要编写自己的任务逻辑，利用线程池提高程序的执行效率和稳定性。