multithreading implementation read, rotate, and save an image using 2 threads - c

Question

I have written this program that should use two threads one that reads in an image into a buffer and the second turns the image 90 degrees and saves it to a file. I need to run this for couple of minutes and collect some data. My problem is that the code runs ok without the while loop counter but I am having issue running multiple times. I assume the problem is with my threaded implementation. When the while loop is include the output image is just a set of vertical lines without the while counter image is reconstructed correctly. thank you
I have written this program that should use two threads one that reads in an image into a buffer and the second turns the image 90 degrees and saves it to a file. I need to run this for couple of minutes and collect some data. My problem is that the problem runs ok without the while loop counter but I am having issue running multiple times. I assume the problem is with my threaded implementation. thank you
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#define WIDTH 512
#define HEIGHT 512
#define DEPTH 255
pthread_mutex_t mtx;
static const unsigned MAX = 8;
char *buffer = (char *)malloc((MAX) * sizeof(char));
void *grab(void *buffer)
{
FILE *infile;
size_t i;
pthread_mutex_lock(&mtx);
char *localbuffer = (char *)buffer;
infile = fopen("lena512.pgm", "r");
for (i = 0; i < 4; ++i)
fscanf(infile, "%*[^\n]\n");
//buffer = (char *)malloc((WIDTH/64) * sizeof(char));
//buffer = (char *)malloc((512) * sizeof(char)); /
for (i = 0; i < HEIGHT; ++i)
{
fread(&localbuffer[i * WIDTH], sizeof(char),
WIDTH, infile);
}
pthread_mutex_unlock(&mtx);
//fclose(infile);
//return localbuffer;
pthread_exit(NULL);
}
void *analyze(void *buffer)
{
pthread_mutex_lock(&mtx);
char *localbuffer = (char *)buffer;
FILE *outfile;
size_t i;
char *analyzed =
(char *)malloc(WIDTH * HEIGHT * sizeof(char));
for (int x = 0; x < WIDTH; x++)
{
for (int y = 0; y < HEIGHT; y++)
{
int offset = HEIGHT * x + y;
analyzed[offset] = localbuffer[y * HEIGHT - 1 + x];
}
}
outfile = fopen("analyzed.pgm", "w");
fputs("P5\n", outfile);
fprintf(outfile, "%d %d\n%d\n", WIDTH, HEIGHT, DEPTH);
for (i = 0; i < HEIGHT; ++i)
{
fwrite(&analyzed[i * WIDTH], sizeof(char),
WIDTH, outfile);
}
pthread_mutex_unlock(&mtx);
//fclose(outfile);
free(analyzed);
//return localbuffer;
pthread_exit(NULL);
}
int main(void)
{
char *localbuffer;
pthread_t thread1, thread2;
int counter = 10000;
while (counter != 0)
{
pthread_create(&thread1, NULL, grab, buffer);
pthread_create(&thread2, NULL, analyze, buffer);
pthread_join(thread1, NULL);
pthread_join(thread2, NULL);
}
return 0;
}