不知道为什么消费者要完成所有工作?
我为带有10个整数的数组的prodcut-consumer创建了一个信号灯,该数组用名称填充,并且返回1和0(二进制)。即使生产者取消信号灯的使用,也会调用使用者。
为什么会这样?
这是代码:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <semaphore.h>
#include <fcntl.h>
#define SIZE 10
#define KEY 1234
int *Memory;
int i, j;
sem_t *sem;
char *name = "Hello";
int main(int argc, const char *argv[])
{
int shmid;
if ((shmid = shmget(KEY, sizeof(int) * SIZE, IPC_CREAT | S_IRWXU)) < 0)
{
perror("Error while creating shmget");
return 1;
}
pid_t pid;
sem = sem_open(name, O_CREAT, S_IRUSR | S_IWUSR, 1);
if ((pid = fork()) != 0)
{
if ((shmid = shmget(KEY, sizeof(int) * SIZE, S_IRWXU)) < 0)
{
perror("error in shmget");
return 1;
}
Memory = (int *)shmat(shmid, NULL, 0);
if (Memory == NULL)
{
perror("error in shmat");
return 1;
}
for (i = 0; i < 10; i++)
{
sem_wait(sem);
Memory[j] = i;
printf("Produced %i in box %i\n", i + 1, i + 1);
sem_post(sem);
sleep(1);
}
int status;
wait(&status);
sem_unlink(name);
sem_destroy(sem);
struct shmid_ds shmid_ds1;
if (shmctl(shmid, IPC_RMID, &shmid_ds1) < 0)
{
perror(
"Error in the father while executing shmctl when it was "
"elimnating the segment of shared memory");
}
}
else
{
if ((shmid = shmget(KEY, sizeof(int) * SIZE, S_IRWXU)) < 0)
{
perror("error in the producer with the shmget");
return 1;
}
Memory = (int *)shmat(shmid, NULL, 0);
if (Memory == NULL)
{
perror("error in the producer with the shmat");
return 1;
}
for (i = 0; i < 10; i++)
{
sem_wait(sem);
Memory[i] = -1;
printf("Consume and now it is %i in box %i\n", Memory[i], i + 1);
sem_post(sem);
}
}
return 0;
}
输出为:
Produced 1 in box 1
Consume and now it is -1 in box 1
Consume and now it is -1 in box 2
Consume and now it is -1 in box 3
Consume and now it is -1 in box 4
Consume and now it is -1 in box 5
Consume and now it is -1 in box 6
Consume and now it is -1 in box 7
Consume and now it is -1 in box 8
Consume and now it is -1 in box 9
Consume and now it is -1 in box 10
Produced 2 in box 2
Produced 3 in box 3
Produced 4 in box 4
Produced 5 in box 5
Produced 6 in box 6
Produced 7 in box 7
Produced 8 in box 8
Produced 9 in box 9
Produced 10 in box 10
最佳答案
#include <pthread.h>
#include <stdio.h>
#include <semaphore.h>
const int max = 5;
int arr[5], f = 0, r = -1;
sem_t s1, s2, sm;
void* eprod(void* pv)
{
int i, x;
printf("Producer Welcome\n");
// sleep(10);
while (1)
{
x = rand() % 100;
printf("producer going to add:%d\n", x);
sem_wait(&s2);
sem_wait(&sm);
// down s2 //buffer may be full
// lock sm
r = (r + 1) % max;
arr[r] = x;
sem_post(&sm);
sem_post(&s1);
sleep(10);
}
// unlock sm
// up s1
}
void* econs(void* pv)
{
int i, x;
printf("Consumer Welcome\n");
while (1)
{
sem_wait(&s1);
sem_wait(&sm);
// down s1
// lock sm
x = arr[f];
f = (f + 1) % max;
printf("Consumer removed element:%d\n", x);
sem_post(&sm);
sem_post(&s2);
// unlock sm
// up s2
// sleep(5);
}
}
int main()
{
pthread_t pt1, pt2;
sem_init(&s1, 0, 0); // 3rd Parameter ival=1
sem_init(&s2, 0, max); // 3rd Parameter ival=1
sem_init(&sm, 0, 1); // 3rd Parameter ival=1
pthread_create(&pt1, NULL, eprod, (void*)0);
pthread_create(&pt2, NULL, econs, (void*)1);
printf("Main Thread is Running\n");
pthread_join(pt1, NULL);
pthread_join(pt2, NULL);
printf("Main -- - - Thanks..!\n");
return 0;
}
希望这可以帮助..