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Aliases: pthread_setattr_default_np(3), pthread_setattr_default_np(3), pthread_setattr_default_np(3)


Manual pages about using GNU/Linux for development


Linux kernel and C library user-space interface documentation


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


#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.


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.


These functions are available in glibc since version 2.18.


For an explanation of the terms used in this section, see attributes(7).
Interface Attribute Value
Thread safety MT-Safe


These functions are nonstandard GNU extensions; hence the suffix "_np" (nonportable) in their names.


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


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