Another Hello World using threads

19 Dec 2009

/*
 * file thread.c
 * compiling: gcc -o thread thread.c -lpthread
 */

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

/*
 * Arguments to print_arg
 */
struct arg
{
  char * str;
  int siz;
};

/*
 * thread function
 */
void *
print_arg (void * arguments)
{
  struct arg * ptr = (struct arg *) arguments;
  write (1, ptr->str, ptr->siz);
}

int
main (void)
{
  struct arg args = {
 "Hello World\n",
 12,
  };

  /* 
   * thread atribute
   */
  pthread_attr_t thread_attr;
  
  /*
   * thread id
   */
  pthread_t thread;
 
  /*
   * init, set to detach, create it
   */
  pthread_attr_init (&thread_attr);
  pthread_attr_setdetachstate (&thread_attr, PTHREAD_CREATE_DETACHED);
  pthread_create (&thread, &thread_attr, &print_arg, &args);
  /*
   * destroy, this don't deallocate things
   */
  pthread_attr_destroy (&thread_attr);
  return 0;
}

Detached thread don't need to return the value to main..
so thread_join isn't needed here... but..
if main return before thread, then thread
is interrupted.. this is what people call bug
sometime works .. sometime not