concurrent threads: segmentation fault

[DCO_81]

Hi,

I have this simple concurrent prog with 2 threads. It compiles fine but when I start it I get a segmentation fault. Why?

#include <pthread.h>
#include <iostream>

using namespace std;

void fun1()
{
	for (int i=0; i < 100; i++)
		cout << "1" << endl;
	pthread_exit(0);
}

void fun2()
{
	for (int i=0; i < 100; i++)
		cout << "2" << endl;
	pthread_exit(0);
}

void concurrent(void (a()), void (b()))
{
	pthread_t pt1, pt2;
	pthread_create(	&pt1,
					NULL,
					(void* (*) (void*)) a,
					NULL);

	pthread_create(	&pt2,
					NULL,
					(void* (*) (void*)) b,
					NULL);
}


void main()
{
	concurrent(fun1, fun2);
}

 

[JankoMuzyk]

your's pthread_t pt1, pt2 variables are local and when function 'concurent' terminates memory that this variables occupied is freed -, threads that you create tries reference to this variables and this is reason of the segmentation fault.

add at end concurrent(void (a()), void (b())) function

this lines:
pthread_join(pt1, NULL);
pthread_join(pt2, NULL);

 

[DCO_81]

Thank you for your tip. I also forgot to link -lpthread and add it to my makefile.