Question

This program creates five threads, each executing the function TaskCode that prints the unique number of this thread to standard output.

My question is how can I create and display the attributes of the threads?

Answer 1

The pthread_attr_init(3) manpage includes a sample program showing how to retrieve the attributes available to threads. Note that the APIs do not allow specifying the pthread_t thread identifier and thus can only return the attributes of the current thread:

   static void
   display_pthread_attr(pthread_attr_t *attr, char *prefix)
   {
       int s, i;
       size_t v;
       void *stkaddr;
       struct sched_param sp;

       s = pthread_attr_getdetachstate(attr, &i);
       if (s != 0)
           handle_error_en(s, "pthread_attr_getdetachstate");
       printf("%sDetach state        = %s\n", prefix,
               (i == PTHREAD_CREATE_DETACHED) ? "PTHREAD_CREATE_DETACHED" :
               (i == PTHREAD_CREATE_JOINABLE) ? "PTHREAD_CREATE_JOINABLE" :
               "???");

       s = pthread_attr_getscope(attr, &i);
       if (s != 0)
           handle_error_en(s, "pthread_attr_getscope");
       printf("%sScope               = %s\n", prefix,
               (i == PTHREAD_SCOPE_SYSTEM)  ? "PTHREAD_SCOPE_SYSTEM" :
               (i == PTHREAD_SCOPE_PROCESS) ? "PTHREAD_SCOPE_PROCESS" :
               "???");

       s = pthread_attr_getinheritsched(attr, &i);
       if (s != 0)
           handle_error_en(s, "pthread_attr_getinheritsched");
       printf("%sInherit scheduler   = %s\n", prefix,
               (i == PTHREAD_INHERIT_SCHED)  ? "PTHREAD_INHERIT_SCHED" :
               (i == PTHREAD_EXPLICIT_SCHED) ? "PTHREAD_EXPLICIT_SCHED" :
               "???");

       s = pthread_attr_getschedpolicy(attr, &i);
       if (s != 0)
           handle_error_en(s, "pthread_attr_getschedpolicy");
       printf("%sScheduling policy   = %s\n", prefix,
               (i == SCHED_OTHER) ? "SCHED_OTHER" :
               (i == SCHED_FIFO)  ? "SCHED_FIFO" :
               (i == SCHED_RR)    ? "SCHED_RR" :
               "???");

       s = pthread_attr_getschedparam(attr, &sp);
       if (s != 0)
           handle_error_en(s, "pthread_attr_getschedparam");
       printf("%sScheduling priority = %d\n", prefix, sp.sched_priority);

       s = pthread_attr_getguardsize(attr, &v);
       if (s != 0)
           handle_error_en(s, "pthread_attr_getguardsize");
       printf("%sGuard size          = %d bytes\n", prefix, v);

       s = pthread_attr_getstack(attr, &stkaddr, &v);
       if (s != 0)
           handle_error_en(s, "pthread_attr_getstack");
       printf("%sStack address       = %p\n", prefix, stkaddr);
       printf("%sStack size          = 0x%x bytes\n", prefix, v);
   }