Calling thread create function in C - c

Question

If I use the pthread_create() call in an infinite while loop in main, does it create multiple threads each time or will it only create the 2 threads that I need?
while(1){
pthread_create(&thread_1...);
pthread_create(&thread_2...);
}

Answer 1

it creates multiple threads each time.

Answer 2

you can use pthread_cancel to cancel any thread from the process.
Below is one of many ways to handle the termination of thread upon some event/timeout etc..
#include <stdio.h>
#include <signal.h> // for sigaction
#include <stdlib.h> // for exit and
#include <pthread.h> // for pthread
#include <string.h> // for memset
#define TIMEOUT 10
pthread_t tid1, tid2;
void* thread_function1(void *arg)
{
while(1)
{
printf(" thread_function1 invoked\n");
sleep(1); //avoid heavy prints
}
}
void* thread_function2(void *arg)
{
while(1)
{
printf(" thread_function2 invoked\n");
sleep(1); //avoid heavy prints
}
}
static void timer_handler(int sig, siginfo_t *siginfo, void *context)
{
printf("Inside handler function timeout happened \n");
if( sig == SIGALRM)
{
pthread_cancel(tid1);
pthread_cancel(tid2);
//exit(0); to exit from main
}
}
int main()
{
int count = 0;
void *status;
struct sigaction act;
memset (&act, '\0', sizeof(act));
sigemptyset(&act.sa_mask);
/* Use the sa_sigaction field because the handles has two additional parameters */
act.sa_sigaction = timer_handler;
/* The SA_SIGINFO flag tells sigaction() to use the sa_sigaction field, not sa_handler. */
act.sa_flags = SA_SIGINFO;
if (sigaction(SIGALRM, &act, NULL) < 0)
{
perror ("sigaction SIGALRM");
return 1;
}
alarm (TIMEOUT);
pthread_create(&tid1,NULL,thread_function1,NULL);
pthread_create(&tid2,NULL,thread_function2,NULL);
pthread_join(tid1,NULL);
pthread_join(tid2,NULL);
printf(" MIAN ENDS ...BYE BYE \n");
return 0;
}