linux 线程同步、互斥

来源：互联网发布：transmission mac 编辑：程序博客网时间：2024/05/29 05:04
#include <pthread.h>#include <stdio.h>#include <stdlib.h>#include <math.h>#define MAXITEMS 10000#define MAXTHREADS 20int nitems;int buf[MAXITEMS];struct{pthread_mutex_t mutex;int nput;int nval;}put = {PTHREAD_MUTEX_INITIALIZER};struct{pthread_mutex_t mutex;pthread_cond_t cond;int nready;}nready = {PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER};int min(int lhs, int rhs){return lhs > rhs ? rhs:lhs;}void *produce(void *arg){while(1){pthread_mutex_lock(&put.mutex);if(put.nput >= nitems){pthread_mutex_unlock(&put.mutex);return NULL;}buf[put.nput] = put.nval;put.nput++;put.nval++;pthread_mutex_unlock(&put.mutex);pthread_mutex_lock(&nready.mutex);if(nready.nready == 0)pthread_cond_signal(&nready.cond);nready.nready++;pthread_mutex_unlock(&nready.mutex);*((int *)arg) += 1;}}void *consume(void *arg){int i;for(i = 0; i <= nitems; i++){pthread_mutex_lock(&nready.mutex);while(nready.nready == 0){pthread_cond_wait(&nready.cond, &nready.mutex);//pthread_cond_wait()先解锁，再阻塞，返回时再加锁}nready.nready--;pthread_mutex_unlock(&nready.mutex);if(buf[i] != i)printf("buf[%d] = %d\n", i, buf[i]);}return NULL;}int main(int argc, char **argv){int i, nthreads, count[MAXITEMS];pthread_t tid_produce[MAXTHREADS], tid_consume;if(argc != 3){perror("argc error\n");exit(0);}nitems = min(atoi(argv[1]), MAXITEMS);nthreads = min(atoi(argv[2]), MAXTHREADS);pthread_setconcurrency(3);for(i = 0; i < nthreads; i++){count[i] = 0;pthread_create(&tid_produce[i], NULL, produce, &count[i]);}pthread_create(&tid_consume, NULL, consume, NULL);for(i = 0; i < nthreads; i++){pthread_join(tid_produce[i], NULL);printf("count[%d] = %d\n", i, count[i]);}pthread_join(tid_consume, NULL);return 0;}
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