PTHREAD_GETATTR_DEFAULT_NP(Linux Programmer's ManPTHREAD_GETATTR_DEFAULT_NP(3)



NAME
       pthread_getattr_default_np,  pthread_setattr_default_np,	 -  get or set
       default thread-creation attributes

SYNOPSIS
       #define _GNU_SOURCE	       /* See feature_test_macros(7) */
       #include <pthread.h>

       int pthread_getattr_default_np(pthread_attr_t *attr);
       int pthread_setattr_default_np(pthread_attr_t *attr);

       Compile and link with -pthread.

DESCRIPTION
       The pthread_setattr_default_np() function sets the  default  attributes
       used  for  creation  of	a new thread--that is, the attributes that are
       used when pthread_create(3) is called with a second  argument  that  is
       NULL.   The default attributes are set using the attributes supplied in
       *attr, a previously initialized thread  attributes  object.   Note  the
       following details about the supplied attributes object:

       *  The attribute settings in the object must be valid.

       *  The stack address attribute must not be set in the object.

       *  Setting  the	stack  size  attribute to zero means leave the default
	  stack size unchanged.

       The  pthread_getattr_default_np()  function  initializes	  the	thread
       attributes  object  referred to by attr so that it contains the default
       attributes used for thread creation.

ERRORS
       EINVAL (pthread_setattr_default_np()) One of the attribute settings  in
	      attr is invalid, or the stack address attribute is set in attr.

       ENOMEM (pthread_setattr_default_np()) Insufficient memory.

VERSIONS
       These functions are available in glibc since version 2.18.

ATTRIBUTES
       For   an	  explanation	of   the  terms	 used  in  this	 section,  see
       attributes(7).

       +-------------------------------+---------------+---------+
       |Interface		       | Attribute     | Value	 |
       +-------------------------------+---------------+---------+
       |pthread_getattr_default_np(),  | Thread safety | MT-Safe |
       |pthread_setattr_default_np()   |	       |	 |
       +-------------------------------+---------------+---------+
CONFORMING TO
       These  functions are nonstandard GNU extensions; hence the suffix "_np"
       (nonportable) in their names.

EXAMPLE
       The  program  below  uses  pthread_getattr_default_np()	to  fetch  the
       default	thread-creation	 attributes and then displays various settings
       from the returned thread attributes object.  When running the  program,
       we see the following output:

	   $ ./a.out
	   Stack size:		8388608
	   Guard size:		4096
	   Scheduling policy:	SCHED_OTHER
	   Scheduling priority: 0
	   Detach state:	JOINABLE
	   Inherit scheduler:	INHERIT


   Program source

       #define _GNU_SOURCE
       #include <pthread.h>
       #include <stdio.h>
       #include <stdlib.h>
       #include <errno.h>

       #define errExitEN(en, msg) \
			       do { errno = en; perror(msg); \
				    exit(EXIT_FAILURE); } while (0)

       static void
       display_pthread_attr(pthread_attr_t *attr)
       {
	   int s;
	   size_t stacksize;
	   size_t guardsize;
	   int policy;
	   struct sched_param schedparam;
	   int detachstate;
	   int inheritsched;

	   s = pthread_attr_getstacksize(attr, &stacksize);
	   if (s != 0)
	       errExitEN(s, "pthread_attr_getstacksize");
	   printf("Stack size:		%zd\n", stacksize);

	   s = pthread_attr_getguardsize(attr, &guardsize);
	   if (s != 0)
	       errExitEN(s, "pthread_attr_getguardsize");
	   printf("Guard size:		%zd\n", guardsize);

	   s = pthread_attr_getschedpolicy(attr, &policy);
	   if (s != 0)
	       errExitEN(s, "pthread_attr_getschedpolicy");
	   printf("Scheduling policy:	%s\n",
		   (policy == SCHED_FIFO) ? "SCHED_FIFO" :
		   (policy == SCHED_RR) ? "SCHED_RR" :
		   (policy == SCHED_OTHER) ? "SCHED_OTHER" : "[unknown]");

	   s = pthread_attr_getschedparam(attr, &schedparam);
	   if (s != 0)
	       errExitEN(s, "pthread_attr_getschedparam");
	   printf("Scheduling priority: %d\n", schedparam.sched_priority);

	   s = pthread_attr_getdetachstate(attr, &detachstate);
	   if (s != 0)
	       errExitEN(s, "pthread_attr_getdetachstate");
	   printf("Detach state:	%s\n",
		   (detachstate == PTHREAD_CREATE_DETACHED) ? "DETACHED" :
		   (detachstate == PTHREAD_CREATE_JOINABLE) ? "JOINABLE" :
		   "???");

	   s = pthread_attr_getinheritsched(attr, &inheritsched);
	   if (s != 0)
	       errExitEN(s, "pthread_attr_getinheritsched");
	   printf("Inherit scheduler:	%s\n",
		   (inheritsched == PTHREAD_INHERIT_SCHED) ? "INHERIT" :
		   (inheritsched == PTHREAD_EXPLICIT_SCHED) ? "EXPLICIT" :
		   "???");
       }

       int
       main(int argc, char *argv[])
       {
	   int s;
	   pthread_attr_t attr;

	   s = pthread_getattr_default_np(&attr);
	   if (s != 0)
	       errExitEN(s, "pthread_getattr_default_np");

	   display_pthread_attr(&attr);

	   exit(EXIT_SUCCESS);
       }

SEE ALSO
       pthread_attr_getaffinity_np(3), pthread_attr_getdetachstate(3),
       pthread_attr_getguardsize(3), pthread_attr_getinheritsched(3),
       pthread_attr_getschedparam(3), pthread_attr_getschedpolicy(3),
       pthread_attr_getscope(3), pthread_attr_getstack(3),
       pthread_attr_getstackaddr(3), pthread_attr_getstacksize(3),
       pthread_attr_init(3), pthread_create(3), pthreads(7)

COLOPHON
       This page is part of release 4.10 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.



Linux				  2016-08-24	 PTHREAD_GETATTR_DEFAULT_NP(3)