---
name: "pthread_getattr_default_np"
section: "3"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/pthread_getattr_default_np"
---

# pthread\_getattr\_default\_np(3)

get or set default thread-creation attributes

## NAME

pthread\_getattr\_default\_np, pthread\_setattr\_default\_np, - get or set default thread-creation attributes

## LIBRARY

POSIX threads library (*libpthread*, *-lpthread*)

## 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(const pthread\_attr\_t \****attr***);**

## 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)](/pthread_create/3.md) 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.

## ATTRIBUTES

For an explanation of the terms used in this section, see [**attributes**(7)](/attributes/7.md).

| | | |
| --- | --- | --- |
| **Interface** | **Attribute** | **Value** |
| **pthread\_getattr\_default\_np**(), **pthread\_setattr\_default\_np**() | Thread safety | MT-Safe |

## STANDARDS

GNU; hence the suffix "\_np" (nonportable) in their names.

## HISTORY

glibc 2.18.

## EXAMPLES

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);
}
```

## SEE ALSO

[**pthread\_attr\_getaffinity\_np**(3)](/pthread_attr_getaffinity_np/3.md), [**pthread\_attr\_getdetachstate**(3)](/pthread_attr_getdetachstate/3.md), [**pthread\_attr\_getguardsize**(3)](/pthread_attr_getguardsize/3.md), [**pthread\_attr\_getinheritsched**(3)](/pthread_attr_getinheritsched/3.md), [**pthread\_attr\_getschedparam**(3)](/pthread_attr_getschedparam/3.md), [**pthread\_attr\_getschedpolicy**(3)](/pthread_attr_getschedpolicy/3.md), [**pthread\_attr\_getscope**(3)](/pthread_attr_getscope/3.md), [**pthread\_attr\_getstack**(3)](/pthread_attr_getstack/3.md), [**pthread\_attr\_getstackaddr**(3)](/pthread_attr_getstackaddr/3.md), [**pthread\_attr\_getstacksize**(3)](/pthread_attr_getstacksize/3.md), [**pthread\_attr\_init**(3)](/pthread_attr_init/3.md), [**pthread\_create**(3)](/pthread_create/3.md), [**pthreads**(7)](/pthreads/7.md)