Thread: Pthreads problem

Hello everybody,

I'm stuck with pthreads. I want to create a program which will run a persistent number of threads, by that i mean, if the number of threads i want to create is 5, the program should create 5 and if any of them finish, program should create more, so the number of threads which are working should be 5. I hope you understand what i mean, with my poor english
So, my problem is, when i'm trying to pass a var to a thread (that goes like this, 1 line in a file goes to a 1 thread and so on), i'm getting wrong results. That's an example file which is opened and parsed line by line:

Code:

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That's program code:

Code:

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



/* THREADS */
void *thread_function();
int running_threads = 0;


pthread_mutex_t pthr_running = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_t accounts = PTHREAD_MUTEX_INITIALIZER;
/***Global vars***/



main(int argc , char *argv[])
{
     	/* FILE */
	FILE *file;
	file = fopen("h.txt" , "r");
	
	int NTHREADS = atoi(argv[1]);
	pthread_t thread_id[NTHREADS];
	
	int TERM = 0;
	int i;
	int linecounter = 0;
	
	while (! TERM) {
		/* Get number of threads to create */
		int pthr_for_create = NTHREADS - running_threads;
		/* check if we need any */
		if (pthr_for_create != 0 && pthr_for_create <= NTHREADS) {
			/* Start creating them */
			for(i = 0; i < pthr_for_create; i++)
   			{ 
      				char line[100];
			        int loop_num = 0;	
				while(fgets(line , 100 , file) != NULL) {
					if (linecounter == loop_num) {
						linecounter++;
						break;
					}
					else {
						loop_num++;
					}
				}
				linecounter++;
				
				
				/* Create */
				pthread_create( &thread_id[i], NULL, thread_function, (void *)line);
				
				
			}
		}
		/* Let finish any thread */
		sleep (1);
	}
	fclose(file);
	exit(0);
}

void *thread_function(void *account)
{
	pthread_mutex_lock( &pthr_running );
   		running_threads++;
   	pthread_mutex_unlock( &pthr_running );
	
	
	
		printf("\tWorking -> %d , Account-> %s" , pthread_self , account);
	
	
	sleep(1);


		printf("\t\t%d <- Finished\n" , pthread_self);

	pthread_mutex_lock( &pthr_running );
   		running_threads--;
   	pthread_mutex_unlock( &pthr_running );


	void *to_exit;
	pthread_exit(to_exit);
}

And that's what i've got:

Code:

        Working -> 4199040 , Account-> 9
        Working -> 4199040 , Account-> 9
        Working -> 4199040 , Account-> 16
        Working -> 4199040 , Account-> 20
        Working -> 4199040 , Account-> 20
                4199040 <- Finished
                4199040 <- Finished
                4199040 <- Finished
                4199040 <- Finished
                4199040 <- Finished
        Working -> 4199040 , Account-> 20
        Working -> 4199040 , Account-> 20
        Working -> 4199040 , Account-> 20
                4199040 <- Finished
                4199040 <- Finished
                4199040 <- Finished
        Working -> 4199040 , Account-> 20
        Working -> 4199040 , Account-> 20
        Working -> 4199040 , Account-> 20
        Working -> 4199040 , Account-> 20
        Working -> 4199040 , Account-> 20
                4199040 <- Finished
                4199040 <- Finished

I understand that i didn't make a check function, to check if it's a last line to pass to a thread, and we should stop, so that's why i have so many "Account-> 20", but i don't understand why it's going like "9 9 16 20 20" , sometimes it's "9 9 9 16 20", and i want it to be like "1 2 3 4 5"

Thanks for help

I understand that, but, new "line" var is initiated every time when it comes to a "for" loop, or it's not? I thought when i'm going through the "for" loop, var "line" is initiated every time, and there is a memory space allocated for every "line" var or it's the same "line" var which is used every time?
I'm a perl programmer

Ok, i get it, thank you very much