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針對某個類正在處理生產者和消費者問題，並且無法進行最後的修改。我遇到的問題是，我認爲我的互斥鎖並沒有鎖定我的線程功能。例如，如果我運行該程序並將其傳遞給參數2 4 4 7，它將打印8 7，然後2秒鐘後它將打印8 8和8 9，等等。我嘗試過使用trylock並在信號量周圍移動，但無濟於事。有沒有什麼東西是我失蹤的時候，導致沒有線程被鎖定？無法獲取互斥鎖來防止線程訪問某個函數
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <semaphore.h>
typedef int buffer_item;
#define BUFFER_SIZE 5
#define TRUE 1
buffer_item START_NUMBER;
int counter;
int insert_item(buffer_item item);
int remove_item(buffer_item *item);
buffer_item buffer[BUFFER_SIZE];
void* producer(void *ptr);
void* consumer(void *ptr);
pthread_cond_t condc, condp;
pthread_mutex_t mutex;
int sleepTime, producerThreads, consumerThreads,a;
pthread_attr_t attr;
sem_t full, empty;
int insert_item(buffer_item item)
{
if(counter < BUFFER_SIZE) {
buffer[counter] = item;
counter++;
return 0;
}
else {
return -1;
}
}
int remove_item(buffer_item *item)
{
if(counter > 0) {
*item = buffer[(counter-1)];
counter--;
return 0;
}
else {
return -1;
}
}
void* producer(void *ptr) {
buffer_item item;
item = START_NUMBER;
while(TRUE) {
sleep(sleepTime);
sem_wait(&empty);
pthread_mutex_lock(&mutex);
if(insert_item(item)) {
fprintf(stderr, "error \n");
}
else {
printf("producer%u produced %d\n", (unsigned int)pthread_self(),item);
item++;
}
pthread_mutex_unlock(&mutex);
sem_post(&full);
}
}
void* consumer(void *ptr) {
buffer_item item;
while(TRUE) {
sleep(sleepTime);
sem_wait(&full);
pthread_mutex_lock(&mutex);
if(remove_item(&item)) {
fprintf(stderr, "error \n");
}
else {
printf("consumer%u consumed %d\n", (unsigned int)pthread_self(),item);
}
pthread_mutex_unlock(&mutex);
sem_post(&empty);
}
}
void initializeData() {
pthread_mutex_init(&mutex, NULL);
sem_init(&full, 0, 0);
sem_init(&empty, 0, BUFFER_SIZE);
pthread_attr_init(&attr);
counter = 0;
}
int main(int argc, char **argv) {
sleepTime = atoi(argv[1]);
producerThreads = atoi(argv[2]);
consumerThreads = atoi(argv[3]);
START_NUMBER = atoi(argv[4]);
initializeData();
pthread_t pro, con;
pthread_mutex_init(&mutex, NULL);
pthread_cond_init(&condc, NULL);
pthread_cond_init(&condp, NULL);
for(a=0; a< consumerThreads;a++)
pthread_create(&con, NULL, consumer, NULL);
for(a=0;a<producerThreads;a++)
pthread_create(&pro, NULL, producer, NULL);
pthread_join(con, NULL);
pthread_join(pro, NULL);
pthread_mutex_destroy(&mutex);
pthread_cond_destroy(&condc);
pthread_cond_destroy(&condp);
sleep(sleepTime);
}
你期待什麼輸出？ – Dmitri
啊我的錯誤，預期的輸出是數字遞增，從一開始 生產者12323112採取在4參數開始生產了7 製片12312310生產的8 消費者1321312消耗7 製片人...... 9 消費者.. ...消耗8' – nojames
因爲每個（生產者）線程都以自己的'item'變量開始，初始化爲'START_NUMBER'。因爲他們每個人都使用和增加他們自己的本地副本，所以每個編號都會得到與生產者相同數量的副本，每個副本顯示兩次，一次產生一次，一次消耗 - 四次生產者線程八次。 – Dmitri