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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | ERRORS | ATTRIBUTES | STANDARDS | HISTORY | EXAMPLES | SEE ALSO | COLOPHON |
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pthread_g...efault_np(3) Library Functions Manualpthread_g...efault_np(3)
pthread_getattr_default_np, pthread_setattr_default_np, - get or
set default thread-creation attributes
POSIX threads library (libpthread, -lpthread)
#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(const pthread_attr_t *attr);
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.
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.
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() │ │ │
└──────────────────────────────────────┴───────────────┴─────────┘
GNU; hence the suffix "_np" (nonportable) in their names.
glibc 2.18.
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 <err.h>
#include <pthread.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
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)
errc(EXIT_FAILURE, s, "pthread_attr_getstacksize");
printf("Stack size: %zu\n", stacksize);
s = pthread_attr_getguardsize(attr, &guardsize);
if (s != 0)
errc(EXIT_FAILURE, s, "pthread_attr_getguardsize");
printf("Guard size: %zu\n", guardsize);
s = pthread_attr_getschedpolicy(attr, &policy);
if (s != 0)
errc(EXIT_FAILURE, 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)
errc(EXIT_FAILURE, s, "pthread_attr_getschedparam");
printf("Scheduling priority: %d\n", schedparam.sched_priority);
s = pthread_attr_getdetachstate(attr, &detachstate);
if (s != 0)
errc(EXIT_FAILURE, 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)
errc(EXIT_FAILURE, s, "pthread_attr_getinheritsched");
printf("Inherit scheduler: %s\n",
(inheritsched == PTHREAD_INHERIT_SCHED) ? "INHERIT" :
(inheritsched == PTHREAD_EXPLICIT_SCHED) ? "EXPLICIT" :
"???");
}
int
main(void)
{
int s;
pthread_attr_t attr;
s = pthread_getattr_default_np(&attr);
if (s != 0)
errc(EXIT_FAILURE, s, "pthread_getattr_default_np");
display_pthread_attr(&attr);
exit(EXIT_SUCCESS);
}
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)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.19.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2026-09-09. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.19 2026-02-08 pthread_g...efault_np(3)
Pages that refer to this page: pthread_attr_init(3), pthread_create(3)
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HTML rendering created 2026-09-09 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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