如何在 pthreads 中正确同步线程

我正在使用pthreads和信号量实现生产者-消费者问题。我有 1 个生产者和 2 个消费者。我的生产者从文件中逐个读取字符，并将它们排队到循环队列中。我希望使用者从队列中读取并存储到单独的数组中。我希望读取方式是第一个使用者读取 2 个字符，第二个使用者每读取第 3 个字符。我正在尝试使用pthread_cond_wait()执行此操作，但没有成功。这是我的代码：

#include<iostream>
#include<pthread.h>
#include<fstream>
#include<unistd.h>
#include<semaphore.h>
#include<queue>
#include "circular_queue"
// define queue size
#define QUEUE_SIZE 5
// declare and initialize semaphore and read/write counter
static sem_t mutex,queueEmptyMutex;
//static int counter = 0;
// Queue for saving characters
static Queue charQueue(QUEUE_SIZE);
//static std::queue<char> charQueue;
// indicator for end of file
static bool endOfFile = false;
// save arrays
static char consumerArray1[100];
static char consumerArray2[100];
static pthread_cond_t cond;
static pthread_mutex_t cond_mutex; 
static bool thirdCharToRead = false;
void *Producer(void *ptr)
{
    int i=0;
    std::ifstream input("string.txt");
    char temp;
    while(input>>temp)
    {
        std::cout<<"reached here a"<<std::endl;
        sem_wait(&mutex);
        std::cout<<"reached here b"<<std::endl;
        if(!charQueue.full())
        {
            charQueue.enQueue(temp);
        }
        sem_post(&queueEmptyMutex);
        sem_post(&mutex);
        i++;
        sleep(4);
    }
    endOfFile = true;
    sem_post(&queueEmptyMutex);
    pthread_exit(NULL);
}
void *Consumer1(void *ptr)
{
    int i = 0;
    sem_wait(&queueEmptyMutex);
    bool loopCond = endOfFile;
    while(!loopCond)
    {
        std::cout<<"consumer 1 loop"<<std::endl;
        if(endOfFile)
        {
            loopCond = charQueue.empty();
            std::cout<<loopCond<<std::endl;
            sem_post(&queueEmptyMutex);
        }
       sem_wait(&queueEmptyMutex);

        sem_wait(&mutex);

        if(!charQueue.empty())
        {
            consumerArray1[i] = charQueue.deQueue();
            i++;
            if(i%2==0)
            {
                pthread_mutex_lock(&cond_mutex);
                std::cout<<"Signal cond. i = "<<i<<std::endl;
                thirdCharToRead = true;
                pthread_mutex_unlock(&cond_mutex);
                pthread_cond_signal(&cond);
            }
        }        
        if(charQueue.empty()&&endOfFile)
        {
            sem_post(&mutex);
            sem_post(&queueEmptyMutex);
            break;
        }  
        sem_post(&mutex);
        sleep(2);
        std::cout<<"consumer 1 loop end"<<std::endl;
    }
    consumerArray1[i] = '';
    pthread_exit(NULL);
}
void *Consumer2(void *ptr)
{
    int i = 0;
    sem_wait(&queueEmptyMutex);
    bool loopCond = endOfFile;
    while(!loopCond)
    {
        std::cout<<"consumer 2 loop"<<std::endl;
        if(endOfFile)
        {
            loopCond = charQueue.empty();
            std::cout<<loopCond<<std::endl;
            sem_post(&queueEmptyMutex);
        }
        sem_wait(&queueEmptyMutex);

        sem_wait(&mutex);

        if(!charQueue.empty())
        {
            pthread_mutex_lock(&cond_mutex);
            while(!thirdCharToRead)
            {
                std::cout<<"Waiting for condition"<<std::endl;
                pthread_cond_wait(&cond,&cond_mutex);
            }
            std::cout<<"Wait over"<<std::endl;
            thirdCharToRead = false;
            pthread_mutex_unlock(&cond_mutex);
            consumerArray2[i] = charQueue.deQueue();
            i++;
        }  
        if(charQueue.empty()&& endOfFile)
        {
            sem_post(&mutex);
            sem_post(&queueEmptyMutex);
            break;
        }  
        sem_post(&mutex);
        std::cout<<"consumer 2 loop end"<<std::endl;
        sleep(2);
    }
    consumerArray2[i] = '';
    pthread_exit(NULL);
}
int main()
{
    pthread_t thread[3];
    sem_init(&mutex,0,1);
    sem_init(&queueEmptyMutex,0,1);
    pthread_mutex_init(&cond_mutex,NULL);
    pthread_cond_init(&cond,NULL);
    pthread_create(&thread[0],NULL,Producer,NULL);
    int rc = pthread_create(&thread[1],NULL,Consumer1,NULL);
    if(rc)
    {
        std::cout<<"Thread not created"<<std::endl;
    }
    pthread_create(&thread[2],NULL,Consumer2,NULL);
    pthread_join(thread[0],NULL);pthread_join(thread[1],NULL);pthread_join(thread[2],NULL);
    std::cout<<"First array: "<<consumerArray1<<std::endl;
    std::cout<<"Second array: "<<consumerArray2<<std::endl;
    sem_destroy(&mutex);
    sem_destroy(&queueEmptyMutex);
    pthread_exit(NULL);
}

我遇到的问题是在一次阅读后，消费者 2 在while(!thirdCharToRead)中进入无限循环。有没有更好的方法来实现这一点？