您好，我正在实现一个称为睡眠理发师问题的多线程程序。问题是有一个理发店有N把椅子，如果没有顾客理发师就会睡着，每当顾客进入店理发师就会醒来并开始剪顾客的头发。我使用条件变量而不是信号量。问题是我无法得到我期望的输出。
#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--;
}
此外，当我开始编程输出时应该"Barber is sleeping now"首先打印，但是主线程首先开始运行生产者线程，然后当计数器等于 0 时它打印"Barber is sleeping now"你能帮我解释为什么序列开始错误吗？另一个问题是主线程填满整个缓冲区并开始倒计时（这意味着理发师将在商店满员后开始他的工作。这是一个输出示例，将为您说明。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
我将不胜感激每一个回复，无论如何谢谢
编辑：第一个代码无法正常工作，对此我感到抱歉，我更新了真正的代码。