定义缓冲区大小为10，三个生产者线程，两个消费者线程，linux下利用互斥和状态变量实现生产者和消费者模型

#include <pthread.h>
#include <queue>
#include <stdio.h>
#include <unistd.h>
using namespace std;

#define MAX_MSG_LEN 10
pthread_mutex_t mutex;
pthread_cond_t condvar_p, condvar_c;

queue<int> msgQueue;

void *producer(void *args)
{
	int threadid = *(int*)args;

	for (int i = 0; i < 10; ++i) {
		usleep(10 * 1000);

		// try to consume a box
		pthread_mutex_lock(&mutex);
		if (msgQueue.size() >= MAX_MSG_LEN) {
			pthread_cond_wait(&condvar_c, &mutex);
		}
		// produce a product
		printf("Thread %d Produce message %d\n", threadid, i);
		msgQueue.push(i);
		pthread_mutex_unlock(&mutex);

		// signal consumer threads
		pthread_cond_signal(&condvar_p);

	}
	pthread_exit((void *)0);
	return NULL;
}

void *consumer(void *args)
{
	int threadid = *(int *)args;
//	usleep(10*1000);
	while (true) {
//		usleep(10 * 1000);
		pthread_mutex_lock(&mutex);
		if (msgQueue.size() <= 0) {
			pthread_cond_wait(&condvar_p, &mutex);
		}
		if (msgQueue.size() > 0) {
			printf("Thread %d consume message %d\n", threadid, msgQueue.front());
			msgQueue.pop();
		}
		pthread_mutex_unlock(&mutex);

		pthread_cond_signal(&condvar_c);
	}
	pthread_exit((void *)0);
	return NULL;
}

int main()
{
	pthread_mutex_init(&mutex, NULL);
	pthread_cond_init(&condvar_p, NULL);
	pthread_cond_init(&condvar_c, NULL);

	pthread_t producer1, producer2, producer3, consumer1, consumer2;

	int i = 1, j = 2, k = 3, l = 4, m = 5;
	pthread_create(&producer1, NULL, producer, (void*)&i);
	pthread_create(&producer2, NULL, producer, (void*)&j);
	pthread_create(&producer3, NULL, producer, (void*)&k);

	pthread_create(&consumer1, NULL, consumer, (void*)&l);
	pthread_create(&consumer2, NULL, consumer, (void*)&m);

	pthread_join(producer1, NULL);
	pthread_join(producer2, NULL);
	pthread_join(producer3, NULL);
	pthread_join(consumer1, NULL);
	pthread_join(consumer2, NULL);
	return 0;
}

g++ main.cpp -std=c++11 -o out -lpthread

可以通过取消代码中的注释，模拟生产者或消费者中的一类或多类线程 阻塞或低效运行时，同步和互斥的作用效果