c - How to sort an array of n elements using n - 1 threads -

i have sort array of n elements using n - 1 threads. each thread test boolean flags equal 0 elements in position i , i+1 have swapped, otherwise set 1. every thread body function ends if elements in right position, flags equal 1.

following main function create threads , join them (some variables global):

int i; pthread_t threads[n - 1];  // init array random values array = init_array(n); len = n;  // flags check if array sorted is_array_sorted = 0; is_sorted = calloc(n - 1, sizeof(int));  // prints initial array print_array(array, n);  // init mutex pthread_mutex_init(&lock, null);  // create n - 1 threads (i = 0; < n - 1; i++) {     if (pthread_create(&threads[i], null, swap, (void*)&i) != 0)         exit(exit_failure); }  // waits until threads end (i = 0; < n - 1; i++) {     if (pthread_join(threads[i], null) != 0)         exit(exit_failure); }  // destroy mutex pthread_mutex_destroy(&lock);  // prints sorted array print_array(array, n);  // free memory free(array); free(is_sorted); 

and thread body function:

static void* swap(void* args) {     // indiex of element check (j , j+1)     int j = *((int*)args);      // while array not sorted     while (1)     {         int i;          // start mutual exclusion         pthread_mutex_lock(&lock);          // check if have swap elements         if (array[j] > array[j+1])         {             // swap elements             int temp = array[j];             array[j] = array[j + 1];             array[j + 1] = temp;         }          // elements in position j , j+1 in right order         is_sorted[j] = 1;         is_array_sorted = 1;          // check if elements sorted         (i = 0; < len - 1; i++)         {             if (is_sorted[i] == 0)             {                 is_array_sorted = 0;                 break;             }         }          if (is_array_sorted)         {             // array sorted, terminate thread             pthread_mutex_unlock(&lock);             break;         }          pthread_mutex_unlock(&lock);     }      pthread_exit(null); } 

the problem program never ends. why? how can fix problem?

please note multithreading exercise performance, or best solution not required.

this code:

for (i = 0; < n - 1; i++) {     if (pthread_create(&threads[i], null, swap, (void*)&i) != 0) 

is not doing think should doing. there 1 variable i, , passing address i threads. i being incremented each time launch thread. there no guarantee each thread see unique value when access data @ passed in address.

a hacky way deal pass in pointer value corresponds integer value want thread receive.

char *x = 0; (i = 0; < n - 1; i++) {     if (pthread_create(&threads[i], null, swap, x++) != 0) 

the thread function decode this:

    int j = (char*)args - (char *)0; 

as stated in comments, sorting approach highly undesirable, , should reworked. think teacher give high marks solution not think highly of abilities of students.