C++ 生产者消费者计数器意外输出的C代码

您好，我正在创建一个简单的计数器，使用生产者-消费者方法来通知一个线程何时完成，以便另一个线程可以运行，这允许它们交替.当我运行代码时，计数按预期从0到10打印了10次.但在计数的每一次打印之间，我得到了十几个锁和解锁的 fingerprint ，以及信号，这让我认为我的代码设置错误.

消费者和生产者端的每个迭代不应该只有一个锁定、解锁和信号吗？输出示例如下:

myCount: 6 -> 7
Producer: signaling myCond1
Producer: waiting on myCond2
CONSUMER: myMutex locked
CONSUMER: signaling myCond2
CONSUMER: myMutex unlocked
Producer: myMutex unlocked
Producer: myMutex locked
CONSUMER: myMutex locked
CONSUMER: signaling myCond2
CONSUMER: myMutex unlocked
myCount: 7 -> 8
Producer: signaling myCond1
Producer: waiting on myCond2
CONSUMER: myMutex locked
CONSUMER: signaling myCond2
CONSUMER: myMutex unlocked
Producer: myMutex unlocked
Producer: myMutex locked
CONSUMER: myMutex locked
CONSUMER: signaling myCond2
CONSUMER: myMutex unlocked
myCount: 8 -> 9
Producer: signaling myCond1
Producer: waiting on myCond2
CONSUMER: myMutex locked
CONSUMER: signaling myCond2
CONSUMER: myMutex unlocked
Producer: myMutex unlocked
Producer: myMutex locked
CONSUMER: myMutex locked
CONSUMER: signaling myCond2
CONSUMER: myMutex unlocked
myCount: 9 -> 10
Producer: signaling myCond1
Producer: waiting on myCond2
CONSUMER: myMutex locked
CONSUMER: signaling myCond2
Producer: myMutex unlocked
Producer: myMutex locked
PROGRAM END

以下是代码:

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

// Global variables
pthread_mutex_t myMutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t myCond1 = PTHREAD_COND_INITIALIZER;
pthread_cond_t myCond2 = PTHREAD_COND_INITIALIZER;
int myCount = 0;

// Function prototypes
void* producerThread(void* arg);
void* consumerThread(void* arg);

int main() {
    // Create consumer thread
    pthread_t consumer;
    printf("PROGRAM START\n");

    if (pthread_create(&consumer, NULL, consumerThread, NULL) != 0) {
        perror("Error creating consumer thread");
        exit(EXIT_FAILURE);
    }

    // Run the producer thread
    producerThread(NULL);

    // Wait for the consumer thread to finish
    pthread_join(consumer, NULL);

    printf("PROGRAM END\n");

    return 0;
}

void* producerThread(void* arg) {
    while (1) {
        printf("Producer: myMutex locked\n");
        pthread_mutex_lock(&myMutex);
        
        if (myCount >= 10) {
            pthread_mutex_unlock(&myMutex);
            break;  // Terminate the program when myCount reaches 10
        }

        myCount++;
        printf("myCount: %d -> %d\n", myCount - 1, myCount);

        // Signal the consumer that a new value is available
        printf("Producer: signaling myCond1\n");
        pthread_cond_signal(&myCond1);

        printf("Producer: waiting on myCond2\n");
        pthread_cond_wait(&myCond2, &myMutex);

        pthread_mutex_unlock(&myMutex);
        printf("Producer: myMutex unlocked\n");
    }

    return NULL;
}

void* consumerThread(void* arg) {
    printf("CONSUMER THREAD CREATED\n");

    while (1) {
        pthread_mutex_lock(&myMutex);
        printf("CONSUMER: myMutex locked\n");

        // Wait for the producer to signal that a new value is available
        while (myCount == 0) {
            printf("CONSUMER: waiting on myCond1\n");
            pthread_cond_wait(&myCond1, &myMutex);
        }

        // Signal the producer that the value has been consumed
        printf("CONSUMER: signaling myCond2\n");
        pthread_cond_signal(&myCond2);

        if (myCount >= 10) {
            pthread_mutex_unlock(&myMutex);
            break;  // Terminate the program when myCount reaches 0
        }
        
        pthread_mutex_unlock(&myMutex);
        printf("CONSUMER: myMutex unlocked\n");
    }

    return NULL;
}