pthread_getattr_default_np(3) [xfree86 man page]

PTHREAD_GETATTR_DEFAULT_NP(3)				     Linux Programmer's Manual				     PTHREAD_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
", stacksize);

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

	   s = pthread_attr_getschedpolicy(attr, &policy);
	   if (s != 0)
	       errExitEN(s, "pthread_attr_getschedpolicy");
	   printf("Scheduling policy:	%s
",
		   (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
", schedparam.sched_priority);

	   s = pthread_attr_getdetachstate(attr, &detachstate);
	   if (s != 0)
	       errExitEN(s, "pthread_attr_getdetachstate");
	   printf("Detach state:	%s
",
		   (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
",
		   (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 4.15 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								    2017-09-15					     PTHREAD_GETATTR_DEFAULT_NP(3)