互斥量

来源：互联网发布：java程序员怎么认证编辑：程序博客网时间：2024/05/16 15:09
#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <pthread.h>#include <errno.h>#define     MAXNITEMS        1000000#define     MAXNTHREADS     100int nitems;struct{    pthread_mutex_t     mutex;    int                 buff[MAXNITEMS];    int                 nput;    int                 nval;} shared = {    PTHREAD_MUTEX_INITIALIZER};void *produce(void*);void *consume(void*);int main(int argc,char *argv[]){    int     i,nthreads,count[MAXNTHREADS];    pthread_t tid_produce[MAXNTHREADS],tid_consume;    if(argc != 3)    {        printf("usage: producongs2 <#itmes> <#threads>.\n");        exit(0);    }    nitems = atoi(argv[1]);    nthreads = atoi(argv[2]);    pthread_setconcurrency(nthreads);  //设置线程并发级别    for(i=0;i<nthreads;++i)    {        count[i] = 0;        pthread_create(&tid_produce[i],NULL,produce,&count[i]);    }    for(i=0;i<nthreads;i++)    {        pthread_join(tid_produce[i],NULL); //等待线程退出        printf("count[%d] = %d\n",i,count[i]);    }    pthread_create(&tid_consume,NULL,consume,NULL);    pthread_join(tid_consume,NULL);  //等待线程退出    exit(0);}void *produce(void *arg){    for(; ;)    {        pthread_mutex_lock(&shared.mutex); //加锁        if(shared.nput >= nitems)        {            pthread_mutex_unlock(&shared.mutex); //释放锁            return ;        }        shared.buff[shared.nput] = shared.nval;        shared.nput++;        shared.nval++;        pthread_mutex_unlock(&shared.mutex); //加锁        *((int*) arg) += 1;    }}void *consume(void *arg){    int     i;    for(i=0;i<nitems;i++)    {        if(shared.buff[i] != i)            printf("buff[%d] = %d\n",i,shared.buff[i]);    }    return;}
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