C编程分段错误: 11个线程问题

Question

当我运行我的代码时为什么会发生这个错误？错误：RUN FINISHED; Segmentation fault: 11; real time: 3s; user: 0ms; system: 0m

我创建了10个线程，每个线程都是一个售票者。有一个10x10的数组，用来存放门票的座位。根据售票者的类型，一个人将被卖给那个特定的座位。

问题出在pthread上吗？

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

/* 
 * File:   ticketsellers.c
 * Author: iantheflyinghawaiian
 *
 * Created on July 4, 2016, 11:27 AM
 */

#include <stdio.h>
#include <pthread.h>
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
// seller thread to serve one time slice (1 minute)

int theatre[10][10] ;

struct node
{
    int info;
    struct node *ptr;
}*front,*rear,*temp,*front1;

int count = 0;

/* Create an empty queue */
void create()
{
    front = rear = NULL;
}

/* Returns queue size */
void queuesize()
{
    printf("\n Queue size : %d", count);
}

/* Enqueing the queue */
void enq(int data)
{
    if (rear == NULL)
    {
        rear = (struct node *)malloc(1*sizeof(struct node));
        rear->ptr = NULL;
        rear->info = data;
        front = rear;
    }
    else
    {
        temp=(struct node *)malloc(1*sizeof(struct node));
        rear->ptr = temp;
        temp->info = data;
        temp->ptr = NULL;

        rear = temp;
    }
    count++;
}

/* Displaying the queue elements */
void display()
{
    front1 = front;

    if ((front1 == NULL) && (rear == NULL))
    {
        printf("Queue is empty");
        return;
    }
    while (front1 != rear)
    {
        printf("%d ", front1->info);
        front1 = front1->ptr;
    }
    if (front1 == rear)
        printf("%d", front1->info);
}

/* Dequeing the queue */
void deq()
{
    front1 = front;

    if (front1 == NULL)
    {
        printf("\n Error: Trying to display elements from empty queue");
        return;
    }
    else
        if (front1->ptr != NULL)
        {
            front1 = front1->ptr;
            printf("\n Dequed value : %d", front->info);
            free(front);
            front = front1;
        }
        else
        {
            printf("\n Dequed value : %d", front->info);
            free(front);
            front = NULL;
            rear = NULL;
        }
        count--;
}

/* Returns the front element of queue */
int frontelement()
{
    if ((front != NULL) && (rear != NULL))
        return(front->info);
    else
        return 0;
}

/* Display if queue is empty or not */
void empty()
{
     if ((front == NULL) && (rear == NULL))
        printf("\n Queue empty");
    else
       printf("Queue not empty");
}



//Ticket Seller
void * sell(char *seller_type)
{
    char seller_type1;
    seller_type1 = *seller_type;
    int i;
    i = 0;
 while (i == 0);
 {
 pthread_mutex_lock(&mutex);
 pthread_cond_wait(&cond, &mutex);
 pthread_mutex_unlock(&mutex);
 // Serve any buyer available in this seller queue that is ready
 // now to buy ticket till done with all relevant buyers in their queue
 //………………
 // Case statements for seller_types
    switch(seller_type1)
    {
        case 'H' :
            printf("Seller type: H\n");
            i = 1;
            break;
        case 'M' :
            printf("Seller type: M\n");
            i = 1;
            break;
        case 'L' :
            printf("Seller type: L\n");
            i = 1;
            break;
    }
 }
 return NULL; // thread exits
}
void wakeup_all_seller_threads()
{
 pthread_mutex_lock(&mutex);
 pthread_cond_broadcast(&cond);
 pthread_mutex_unlock(&mutex);
}
int main()
{
 int i, N;
 pthread_t tids[10];
 printf("Enter N value of Customers: ");
 scanf("%d", &N);
 printf("Number of Customers: %d", N);

 char seller_type;
 // Create necessary data structures for the simulator.
 // Create buyers list for each seller ticket queue based on the
 // N value within an hour and have them in the seller queue.
 // Create 10 threads representing the 10 sellers.
 seller_type = 'H';
 pthread_create(&tids[i], NULL, sell, &seller_type);
 seller_type = 'M';

 for (i = 1; i < 4; i++)
 pthread_create(&tids[i], NULL, sell, &seller_type);
 seller_type = 'L';
 for (i = 4; i < 10; i++)
 pthread_create(&tids[i], NULL, sell, &seller_type);
 // wakeup all seller threads
 wakeup_all_seller_threads();

 // wait for all seller threads to exit
 for (i = 0 ; i < 10 ; i++)
    pthread_join(&tids[i], NULL);
 // Printout simulation results
 //…………
 exit(0);
}