2.根据C语言和Pthread编写:有三个并发进程和缓冲区,进程input每次输入一条记录到缓冲区,进程process每次都从缓冲区取出一条记录并处理,然后再将处理的记录放回缓冲区,进程output每次从缓冲区取出一条处理好的记录并进行输出,注意避免记录覆盖,重复读取未经处理等问题。
时间: 2024-03-22 17:42:20 浏览: 33
好的,我可以帮你实现这个程序。下面是程序的代码:
```
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#define BUFFER_SIZE 10
#define RECORD_SIZE 100
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t full = PTHREAD_COND_INITIALIZER;
pthread_cond_t empty = PTHREAD_COND_INITIALIZER;
int buffer[BUFFER_SIZE];
int in = 0;
int out = 0;
int count = 0;
void *input(void *arg) {
int record_count = 0;
while (record_count < 30) {
pthread_mutex_lock(&mutex);
while (count == BUFFER_SIZE) {
pthread_cond_wait(&empty, &mutex);
}
buffer[in] = record_count;
in = (in + 1) % BUFFER_SIZE;
count++;
printf("Input: %d\n", record_count);
pthread_cond_signal(&full);
pthread_mutex_unlock(&mutex);
record_count++;
}
return NULL;
}
void *process(void *arg) {
int record_count = 0;
while (record_count < 30) {
pthread_mutex_lock(&mutex);
while (count == 0) {
pthread_cond_wait(&full, &mutex);
}
int record = buffer[out];
out = (out + 1) % BUFFER_SIZE;
count--;
record = record * 2; // 处理记录
printf("Process: %d\n", record);
buffer[in] = record;
in = (in + 1) % BUFFER_SIZE;
count++;
pthread_cond_signal(&empty);
pthread_mutex_unlock(&mutex);
record_count++;
}
return NULL;
}
void *output(void *arg) {
int record_count = 0;
while (record_count < 30) {
pthread_mutex_lock(&mutex);
while (count == 0) {
pthread_cond_wait(&full, &mutex);
}
int record = buffer[out];
out = (out + 1) % BUFFER_SIZE;
count--;
printf("Output: %d\n", record);
pthread_cond_signal(&empty);
pthread_mutex_unlock(&mutex);
record_count++;
}
return NULL;
}
int main() {
pthread_t tid1, tid2, tid3;
pthread_create(&tid1, NULL, input, NULL);
pthread_create(&tid2, NULL, process, NULL);
pthread_create(&tid3, NULL, output, NULL);
pthread_join(tid1, NULL);
pthread_join(tid2, NULL);
pthread_join(tid3, NULL);
return 0;
}
```
我们使用了三个线程来实现三个并发进程。线程`input`负责将记录写入缓冲区,线程`process`负责从缓冲区取出记录并处理,然后再将处理好的记录写回缓冲区,线程`output`负责从缓冲区取出处理好的记录并输出。为了避免记录覆盖和重复读取未经处理的记录,我们使用了互斥锁和条件变量来对缓冲区进行同步。线程`input`和`process`在向缓冲区写入记录和读取记录时,需要检查缓冲区是否已满或为空,如果是则阻塞等待。线程`process`在处理完记录后,会将处理好的记录写回到缓冲区中,线程`output`在读取记录时,也需要检查缓冲区是否已满或为空,如果是则阻塞等待。这样可以保证程序的正确性和稳定性。
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