Pthread Introduction Part 2

In the previous chapter we saw how to create a thread and how to join and detach thread.

In this chapter we shall further see, what are the different thread functions available to us.

1. To get the ID of a thread, use below API:

pthread_t pthread_self(void);

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <pthread.h>

//for more tutorials on C, C++, STL, DS, Linux visit www.ProDeveloperTutorial.com


void* func(void* p) 
{
   printf("The thread id = %d\n", pthread_self()); 
      pthread_exit(NULL);

   return NULL;
}

int main() 
{
   pthread_t thread;
    
   pthread_create(&thread, NULL, func, NULL);
   printf("From the main function, the thread id = %d\n", thread);

   pthread_join(thread, NULL);

   return 0;
}

Output;

From the main function, the thread id = 120414208
The thread id = 120414208

2. To compare 2 different threads, use below API:

int pthread_equal(pthread_t tid1, pthread_t tid2);

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <pthread.h>

//for more tutorials on C, C++, STL, DS, Linux visit www.ProDeveloperTutorial.com

pthread_t thread_1_id;

void* func(void* p) 
{
   printf("The thread id = %d\n", pthread_self()); 

   if( pthread_equal(thread_1_id, pthread_self()) )
   {
   	   printf("\n Both of the threads are equal");
   }
   else
   {
   	   printf("\n Both threads are not equal");
   }

   pthread_exit(NULL);

   return NULL;
}

int main() 
{
   pthread_t thread;

   pthread_create(&thread, NULL, func, NULL);
   printf("\nFrom the main function, the thread id = %d", thread);

   thread_1_id = thread;

   pthread_join(thread, NULL);

   return 0;
}

Output:

From the main function, the thread id = 29249536

The thread id = 29249536

Both of the threads are equal

 

3. To initialize a routing only once, use below API. The subsequent call will not have any effect.

int pthread_once(pthread_once_t *once_control, void (*init_routine)(void));

4. To set priority to a thread use below API:

int pthread_setschedparam(pthread_t tid, int policy, const struct sched_param *param);

Priority should be set before creating a thread.

5. To get the priority of a thread, use below API:

int pthread_getschedparam(pthread_t tid, int policy, struct schedparam *param);

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <pthread.h>
#include <sched.h>

//for more tutorials on C, C++, STL, DS, Linux visit www.ProDeveloperTutorial.com


void* func(void* p) 
{
   pthread_exit(NULL);

   return NULL;
}

int main() 
{
   pthread_t thread;
   pthread_attr_t tattr;
   int ret;
   struct sched_param param;
   int policy = 0;

   
   printf ("The priority is = %d\n", pthread_getschedparam(thread, &policy, &param));

   pthread_create(&thread, &tattr, func, NULL);
   
   pthread_join(thread, NULL);

   return 0;
}

Output:

The priority is = 3

6. To send a signal to a thread, use below API:
pthread_kill(tid, sig);

7. To terminate a thread, use below API:
pthread_exit(&status); /* exit with status */

8. To cancel a thread, use below API:
pthread_cancel(thread);