multi-thread programming

gcc test-thread1.c -lpthread

1) test-thread1.c
Multithreading — Waiting for other threads
It is also possible to make one thread stop and wait for another thread to finish. This is accomplished with pthread_join

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

/* This is our thread function.  It is like main(), but for a thread */
void *threadFunc(void *arg)
{
 char *str;
 int i = 0;

 str=(char*)arg;

 while(i < 10 )
 {
  usleep(1);
  printf("threadFunc says: %s\n",str);
  ++i;
 }

 return NULL;
}

int main(void)
{
 pthread_t pth; // this is our thread identifier
 int i = 0;

 /* Create worker thread */
 pthread_create(&pth,NULL,threadFunc,"processing...");

 /* wait for our thread to finish before continuing */
 pthread_join(pth, NULL /* void ** return value could go here */);

 while(i < 10 )
 {
  usleep(1);
  printf("main() is running...\n");
  ++i;
 }

 return 0;
}

2) in test-thread2.c, if we put pthread_join after while loop
in main(). We can see alternating lines as the main() and threadFunc() threads execute and pause.

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

/* This is our thread function.  It is like main(), but for a thread*/
void *threadFunc(void *arg)
{
 char *str;
 int i = 0;

 str=(char*)arg;

 while(i < 110 )
 {
  usleep(1);
  printf("threadFunc says: %s\n",str);
  ++i;
 }

 return NULL;
}

int main(void)
{
 pthread_t pth; // this is our thread identifier
 int i = 0;

 pthread_create(&pth,NULL,threadFunc,"foo");
 
 while(i < 100)
 {
  usleep(1);
  printf("main is running...\n");
  ++i;
 }

 printf("main waiting for thread to terminate...\n");
 pthread_join(pth,NULL);

 return 0;
}