生产者消费者计划使用信号量和pthreads

我已经为生产者 – 消费者问题写了一个代码。但是我没有得到输出。没有编译错误，但在我的程序中发出警告。我很困惑。非常努力。但是无法得到它。请告诉我什么在我的程序中是错误的。什么是正确的程序。我感到沮丧。请帮助伙计们。 这是代码 –

#include  #include  #include  #include  #define BUFF_SIZE 5 /* total number of slots */ #define NP 3 /* total number of producers */ #define NC 3 /* total number of consumers */ #define NITERS 4 /* number of items produced/consumed */ typedef struct { int buf[BUFF_SIZE]; /* shared var */ int in; /* buf[in%BUFF_SIZE] is the first empty slot */ int out; /* buf[out%BUFF_SIZE] is the first full slot */ sem_t full; /* keep track of the number of full spots */ sem_t empty; /* keep track of the number of empty spots */ sem_t mutex; /* enforce mutual exclusion to shared data */ } sbuf_t; sbuf_t shared; void *Producer(void *arg) { int i, item, index; index = (int) arg; for (i = 0; i  0; i--) { sem_wait(&shared.full); sem_wait(&shared.mutex); item = i; item = shared.buf[shared.out]; shared.out = (shared.out + 1) % BUFF_SIZE; printf("[C%d] Consuming %d ...\n", index, item); fflush(stdout); /* Release the buffer */ sem_post(&shared.mutex); /* Increment the number of full slots */ sem_post(&shared.empty); /* Interleave producer and consumer execution */ if (i % 2 == 1) sleep(1); } return NULL; } int main() { pthread_t idP, idC; int index; sem_init(&shared.full, 0, 0); sem_init(&shared.empty, 0, BUFF_SIZE); pthread_mutex_init(&shared.mutex, NULL); for (index = 0; index < NP; index++) { /* Create a new producer */ pthread_create(&idP, NULL, Producer, (void*)index); } /*create a new Consumer*/ for (index = 0;index < NC;index++) { pthread_create(&idC, NULL, Consumer, (void*)index); } pthread_exit(NULL); } 

Answer 1

也许你应该把编译器警告更严重。 不正确的类型和未定义的函数通常显示为警告…

我没有检查你的程序的逻辑，但原则应该工作：

 #include  #include  #include  #include  // for sleep #include  #define BUFF_SIZE 5 /* total number of slots */ #define NP 3 /* total number of producers */ #define NC 3 /* total number of consumers */ #define NITERS 4 /* number of items produced/consumed */ typedef struct { int buf[BUFF_SIZE]; /* shared var */ int in; /* buf[in%BUFF_SIZE] is the first empty slot */ int out; /* buf[out%BUFF_SIZE] is the first full slot */ sem_t full; /* keep track of the number of full spots */ sem_t empty; /* keep track of the number of empty spots */ // use correct type here pthread_mutex_t mutex; /* enforce mutual exclusion to shared data */ } sbuf_t; sbuf_t shared; void *Producer(void *arg) { int i, item, index; index = (int)arg; for (i=0; i < NITERS; i++) { /* Produce item */ item = i; /* Prepare to write item to buf */ /* If there are no empty slots, wait */ sem_wait(&shared.empty); /* If another thread uses the buffer, wait */ pthread_mutex_lock(&shared.mutex); shared.buf[shared.in] = item; shared.in = (shared.in+1)%BUFF_SIZE; printf("[P%d] Producing %d ...\n", index, item); fflush(stdout); /* Release the buffer */ pthread_mutex_unlock(&shared.mutex); /* Increment the number of full slots */ sem_post(&shared.full); /* Interleave producer and consumer execution */ if (i % 2 == 1) sleep(1); } return NULL; } void *Consumer(void *arg) { int i, item, index; index = (int)arg; for (i=NITERS; i > 0; i--) { sem_wait(&shared.full); pthread_mutex_lock(&shared.mutex); item=i; item=shared.buf[shared.out]; shared.out = (shared.out+1)%BUFF_SIZE; printf("[C%d] Consuming %d ...\n", index, item); fflush(stdout); /* Release the buffer */ pthread_mutex_unlock(&shared.mutex); /* Increment the number of full slots */ sem_post(&shared.empty); /* Interleave producer and consumer execution */ if (i % 2 == 1) sleep(1); } return NULL; } int main() { pthread_t idP, idC; int index; sem_init(&shared.full, 0, 0); sem_init(&shared.empty, 0, BUFF_SIZE); pthread_mutex_init(&shared.mutex, NULL); for (index = 0; index < NP; index++) { /* Create a new producer */ pthread_create(&idP, NULL, Producer, (void*)index); } /*create a new Consumer*/ for(index=0; index 

我希望这有帮助。

Answer 2

仍有编译器警告。 从void指针获取整数值的正确方法是：

 index = *(int*)arg; 

并且，也传递一个整数指针，如下所示：

 pthread_create(&idC,NULL,Consumer,(void*)&index); 

我仍然怀疑Consumer或Producer线程将如何接收传递的整数值，因为这是主线程中for循环中索引变量的地址。 一旦索引增加，Consumer或Producer线程就会受到此增量的影响。