Linux编程编程实战（三）

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Linux编程———线程相关

创建函数pthread_create注意事项

错误示例：res = pthread_create(&tid[i],NULL,(void*)thread_func(),NULL);
亦或：res = pthread_create(&tid[i],NULL,(void*)thread_func(argument0,...),NULL);
亦或：res = pthread_create(&tid[i],NULL,(void*)(thread_func(argument0,...)),NULL);

任何在函数名称后紧着括号的情况，函数都将被执行，函数名自然也不会被作为地址传参，也就是说，实际上线程并未创建，尤其实在thread_func()是个死循环的情况下，会给人一种线程开始运行后main线程就停止了错觉，实则是卡死在了thread_func()的死循环中。

哲学家进餐问题

以哲学家进餐问题为示例，实践线程的基础使用
下面贴出代码：

#include<stdio.h>#include<time.h>#include<pthread.h>#include<unistd.h>#include<stdlib.h>#include<sched.h>//全局变量pthread_mutex_t *mutex;pthread_t *tid;int PhilosopherNum = 0; //总数量int PhilosopherNumber = 0;void philosopher(void);void philosopher(void){    int state = 1;     int Philosophernum = PhilosopherNumber++;    srand(time(0));    printf("哲学家%d开始思考了\n",Philosophernum+1);    while(1){        switch(state){            case 0:                sleep(rand()%10);            state = 1;            printf("哲学家%d饿了\n",Philosophernum+1);            break;            case 1:            if(pthread_mutex_trylock(&mutex[Philosophernum]) != 0){                continue;            }            else{                if(pthread_mutex_trylock(&mutex[(Philosophernum+1)%PhilosopherNum]) != 0){                    pthread_mutex_unlock(&mutex[Philosophernum]);                }                else{                    state = 2;                    printf("哲学家%d开始进餐\n",Philosophernum+1);                }            }            break;            case 2:            sleep(rand()%10);            state = 0;            printf("哲学家%d进餐完毕，开始思考了\n",Philosophernum+1);            pthread_mutex_unlock(&mutex[Philosophernum]);            pthread_mutex_unlock(&mutex[(Philosophernum+1)%PhilosopherNum]);            break;            default:            printf("错误状态！！！\n");            exit(0);        }    }}int main(){     int i;    pthread_attr_t attr;    struct sched_param Param;    pthread_attr_init(&attr);    pthread_attr_getschedparam(&attr,&Param);    Param.sched_priority = 20;    pthread_attr_setschedparam(&attr,&Param);    printf("输入哲学家数量：");    scanf("%d",&PhilosopherNum);    if(PhilosopherNum < 2) PhilosopherNum = 5;    mutex = (pthread_mutex_t *)malloc(sizeof(pthread_mutex_t)*PhilosopherNum);    tid = (pthread_t *)malloc(sizeof(pthread_t)*PhilosopherNum);    int res;    for(i = 0;i < PhilosopherNum;i++){        res = pthread_mutex_init(&mutex[i],NULL);        if(res!=0){            printf("互斥量初始化失败!!!\n");            exit(0);        }    }    for(i = 0;i < PhilosopherNum;i++){        printf("%d\n",i);        Param.sched_priority = 20 + i;        pthread_attr_setschedparam(&attr,&Param);        res = pthread_create(&tid[i],NULL,(void*)philosopher,NULL);        if(res!=0){            printf("线程初始化失败!!!\n");            exit(0);        }    }    rewind(stdin);    char key = 0;    while(key != 'q') key = getchar();    for(i = 0;i < PhilosopherNum;i++){        pthread_cancel(&tid[i]);    }    return 0;}

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