Linux多线程编程简例6个

梦里梦外; 2022-06-01 09:40 133阅读 0赞

//创建多线程
    #include <stdio.h>
    #include <string.h>
    #include <stdlib.h>
    #include <pthread.h>
    #include <unistd.h>
    
    pthread_t ntid;
    
    void printids(const char *s)
    {
    	pid_t		pid;
    	pthread_t	tid;
    	
    	pid = getpid();
    	tid = pthread_self();
    	printf("%s pid %u tid %u (0x%x)\n", s, (unsigned int)pid, 
    			(unsigned int)tid, (unsigned int)tid);
    }
    
    void *thr_fn(void *arg)
    {
    	printids(arg);
    	return NULL;
    }
    
    int main(void)
    {
    	int err;
    	
    	err = pthread_create(&ntid, NULL, thr_fn, "new thread:");
    	if(err != 0)
    	{
    		fprintf(stderr, "can't create thread: %s\n", strerror(err));;
    	}
    	
    	printids("main thread:");
    	sleep(1);
    	
    	return 0;
    }

//pthread_join
    #include <stdio.h>
    #include <stdlib.h>
    #include <pthread.h>
    #include <unistd.h>
    
    void *thr_fn1(void *arg)
    {
    	printf("thread 1 returning\n");
    	return (void*)1;
    }
    
    void *thr_fn2(void *arg)
    {
    	printf("thread 2 exiting\n");
    	pthread_exit((void*)2);
    }
    
    void *thr_fn3(void *arg)
    {
    	while(1)
    	{
    		printf("thread 3 writing\n");
    		sleep(1);
    	}
    }
    
    int main(void)
    {
    	pthread_t 	 tid;
    	void 		*tret;
    	
    	pthread_create(&tid, NULL, thr_fn1, NULL);
    	pthread_join(tid, &tret);
    	printf("thread 1 exit code %d\n", (int)tret);
    	
    	pthread_create(&tid, NULL, thr_fn2, NULL);
    	pthread_join(tid, &tret);
    	printf("thread 2 exit code %d\n", (int)tret);
    	
    	pthread_create(&tid, NULL, thr_fn3, NULL);
    	sleep(3);
    	pthread_cancel(tid);
    	pthread_join(tid, &tret);
    	printf("thread 3 exit code %d\n", (int)tret);
    	
    	return 0;
    }

//演示两个线程操作全局变量时相互干扰
    #include <stdio.h>
    #include <stdlib.h>
    #include <pthread.h>
    
    #define NLOOP 5000
    
    int counter;
    
    void *doit(void *);
    
    int main(void)
    {
    	pthread_t tidA, tidB;
    	
    	pthread_create(&tidA, NULL, &doit, NULL);
    	pthread_create(&tidB, NULL, &doit, NULL);
    	
    	pthread_join(tidA, NULL);
    	pthread_join(tidB, NULL);
    	
    	return 0;
    }
    
    void *doit(void *vptr)
    {
    	int i, val;
    	
    	for(i=0; i<NLOOP; i++)
    	{
    		val = counter;
    		printf("%x: %d\n", (unsigned int)pthread_self(), val+1);
    		counter = val + 1;
    	}
    	
    	return NULL;
    }

//演示两个线程操作全局变量时相互干扰， 试用mutex解决
    #include <stdio.h>
    #include <stdlib.h>
    #include <pthread.h>
    
    #define NLOOP 5000
    
    int				counter;
    pthread_mutex_t	counter_mutex = PTHREAD_MUTEX_INITIALIZER;//互斥锁初始化
    
    void *doit(void *);
    
    int main(void)
    {
    	pthread_t tidA, tidB;
    	
    	pthread_create(&tidA, NULL, &doit, NULL);
    	pthread_create(&tidB, NULL, &doit, NULL);
    	
    	pthread_join(tidA, NULL);
    	pthread_join(tidB, NULL);
    	
    	return 0;
    }
    
    void *doit(void *vptr)
    {
    	int i, val;
    	
    	for(i=0; i<NLOOP; i++)
    	{
    		pthread_mutex_lock(&counter_mutex);//获得锁
    		val = counter;
    		printf("%x: %d\n", (unsigned int)pthread_self(), val+1);
    		counter = val + 1;
    		pthread_mutex_unlock(&counter_mutex);//解锁
    	}
    	
    	return NULL;
    }

// pthread_cond,生产者、消费者模型
    #include <stdlib.h>
    #include <pthread.h>
    #include <stdio.h>
    
    struct msg
    {
    	struct msg *next;
    	int num;
    };
    
    struct msg 		*head;
    pthread_cond_t	 has_product = PTHREAD_COND_INITIALIZER;
    pthread_mutex_t	 lock = PTHREAD_MUTEX_INITIALIZER;
    
    void *consumer(void *p)
    {
    	struct msg *mp;
    	
    	for(;;)
    	{
    		pthread_mutex_lock(&lock);
    		while(head == NULL)
    		{
    			pthread_cond_wait(&has_product, &lock);
    			// 线程调用pthread_cond_wait在一个Condition Variable上
    			// 阻塞等待，这个函数做以下三步操作：
    			// 1. 释放Mutex
    			// 2. 阻塞等待
    			// 3. 当被唤醒时，重新获得Mutex并返回 
    		}
    		mp = head;
    		head = mp->next;
    		pthread_mutex_unlock(&lock);
    		
    		printf("Consume -%d\n", mp->num);
    		free(mp);
    		sleep(rand() % 5);
    	}
    	
    	return NULL;
    }
    
    void *producer(void *p)
    {
    	struct msg *mp;
    	
    	for(;;)
    	{
    		mp = malloc(sizeof(struct msg));
    		mp->num = rand() % 1000 + 1;
    		printf("Produce +%d\n", mp->num);
    		
    		pthread_mutex_lock(&lock);
    		mp->next = head;
    		head = mp;
    		pthread_mutex_unlock(&lock);
    		
    		pthread_cond_signal(&has_product);
    		// 线程可以调用pthread_cond_signal唤醒在
    		// 某个Condition Variable上等待的另一个线程
    		sleep(rand() % 5);
    	}
    }
    
    int main()
    {
    	pthread_t pid, cid;
    	
    	pthread_create(&pid, NULL, producer, NULL);
    	pthread_create(&cid, NULL, consumer, NULL);
    	
    	pthread_join(pid, NULL);
    	pthread_join(cid, NULL);
    	
    	return 0;
    }

//sem, 生产者、消费者模型
    #include <stdlib.h>
    #include <pthread.h>
    #include <stdio.h>
    #include <semaphore.h>
    
    #define	NUM	5
    
    sem_t 	blank_number, product_number;
    int 	queue[NUM];
    
    pthread_cond_t	 has_product = PTHREAD_COND_INITIALIZER;
    pthread_mutex_t	 lock = PTHREAD_MUTEX_INITIALIZER;
    
    void *consumer(void *p)
    {
    	int n = 0;
    	
    	for(;;)
    	{
    		sem_wait(&product_number);
    		printf("Consume -%d\n", queue[n]);
    		queue[n] = 0;
    		sem_post(&blank_number);
    		
    		n = (n + 1) % NUM;
    		sleep(rand() % 5);
    	}
    	
    	return NULL;
    }
    
    void *producer(void *arg)
    {
    	int n = 0;
    	
    	for(;;)
    	{
    		sem_wait(&blank_number);
    		queue[n] = rand() % 1000 + 1;
    		printf("Produce +%d\n", queue[n]);
    		sem_post(&product_number);
    		
    		n = (n + 1) % NUM;
    		sleep(rand() % 5);
    	}
    }
    
    int main()
    {
    	pthread_t pid, cid;
    	
    	sem_init(&blank_number, 0, NUM);
    	sem_init(&product_number, 0, 0);
    	
    	pthread_create(&pid, NULL, producer, NULL);
    	pthread_create(&cid, NULL, consumer, NULL);
    	
    	pthread_join(pid, NULL);
    	pthread_join(cid, NULL);
    	
    	sem_destroy(&blank_number);
    	sem_destroy(&product_number);
    	
    	return 0;
    }

参考资料：http://www.eefocus.com/html/09-11/26160910394Yba.shtml