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您好我正在实施一个多线程程序,这就是所谓的睡理发师问题。问题是有一个理发店有N把椅子,如果没有任何顾客理发师会入睡,每当顾客进店时,理发师都会醒来,并开始切断顾客的头发。我使用条件变量而不是信号量。事情是我不能有我期望的输出。关于同步,同时实现多线程熟睡理发师
#include <stdlib.h>
#include <stdio.h>
#include <pthread.h>
#include <time.h>
#define TRUE 1
pthread_mutex_t mutex;
pthread_cond_t fill;
int counter;
int* buffer;
int size;
void* producer(void*);
void* consumer(void*);
void initialize_variables();
void insert(void);
void remove_item(void);
int main(int argc, char *argv[]) {
int random_num;
int num=0;
pthread_t barber;
srand(time(NULL));
if(argc!=2){
printf("Not enough parameters\n");
exit(0);
}
size=atoi(argv[1]);
initialize_variables();
pthread_create(&barber,NULL,consumer,NULL);
while(TRUE){
pthread_t customer;
pthread_create(&customer,NULL,producer,NULL);
}
printf("Exit the program\n");
return 0;
}
void initialize_variables(){
int i;
if(! (buffer=(int*)malloc(size*sizeof(int)))){
printf("Error while allocating memory for buffer\n");
exit(1);
}
for(i=0; i<size; i++)
buffer[i]=0;
pthread_mutex_init(&mutex,NULL);
pthread_cond_init(&empty, NULL);
pthread_cond_init(&fill, NULL);
counter = 0;
}
void* producer(void* arg){
pthread_mutex_lock(&mutex);
while(counter==size)
pthread_cond_wait(&empty,&mutex);
printf("One Customer has arrived and sit on the #%d chair\n", counter);
insert();
sleep(1);
pthread_cond_signal(&fill);
pthread_mutex_unlock(&mutex);
pthread_exit(NULL);
}
void* consumer(void* arg){
while(TRUE){
pthread_mutex_lock(&mutex);
while(counter==0){
printf("Barber is sleeping now\n");
pthread_cond_wait(&fill,&mutex);
}
remove_item();
sleep(1);
pthread_cond_broadcast(&empty);
pthread_mutex_unlock(&mutex);
}
}
void insert(void){
buffer[counter]=1;
counter++;
}
void remove_item(void){
buffer[counter]=0;
printf("The barber is started to cut the hair of the customer at chair #%d\n", counter);
counter--;
}
而且,当我开始输出程序应打印"Barber is sleeping now"
第一,但主线程,然后再开始运行生产线时,计数器等于零它打印"Barber is sleeping now"
你能帮助我,为什么顺序错误开始?另一个问题是主线程填充整个缓冲区并开始倒计时(这指的是理发师在店铺满了之后将开始他的工作,这里是输出的一个例子,它会让你明白,并假设缓冲区大小为10
One Customer has arrived and sit on the #0 chair
One Customer has arrived and sit on the #1 chair
One Customer has arrived and sit on the #2 chair
One Customer has arrived and sit on the #3 chair
One Customer has arrived and sit on the #4 chair
One Customer has arrived and sit on the #5 chair
One Customer has arrived and sit on the #6 chair
One Customer has arrived and sit on the #7 chair
One Customer has arrived and sit on the #8 chair
One Customer has arrived and sit on the #9 chair
The barber is started to cut the hair of the customer at chair #10
The barber is started to cut the hair of the customer at chair #9
The barber is started to cut the hair of the customer at chair #8
The barber is started to cut the hair of the customer at chair #7
The barber is started to cut the hair of the customer at chair #6
The barber is started to cut the hair of the customer at chair #5
The barber is started to cut the hair of the customer at chair #4
The barber is started to cut the hair of the customer at chair #3
The barber is started to cut the hair of the customer at chair #2
The barber is started to cut the hair of the customer at chair #1
Barber is sleeping now
One Customer has arrived and sit on the #0 chair
我可以理解为每一个答复,并感谢反正
编辑:第一代码后不能正常工作抱歉的是,我与真正的一个更新的
是的,你是对的,但不应该是输出打印首先“理发师现在正在睡觉”因为理发线程在生产者线程之前创建? – quartaela
不,这正是我写的。你可以运行profram 100次,看到有时理发师会先开始,有时它不会 – stdcall
好吧,然后我明白了。感谢您的有用信息。 – quartaela