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pthread_getattr_default_np(3) Library Functions Manual pthread_getattr_default_np(3)

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) 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

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

VERSIONS

These functions are available since glibc 2.18.

ATTRIBUTES

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

Interface Attribute Value
pthread_getattr_default_np (), pthread_setattr_default_np () Thread safety MT-Safe

STANDARDS

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

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 <errno.h>
#include <pthread.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:          %zd\n", stacksize);


    s = pthread_attr_getguardsize(attr, &guardsize);


    if (s != 0)


        errc(EXIT_FAILURE, s, "pthread_attr_getguardsize");


    printf("Guard size:          %zd\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_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)

2023-02-05 Linux man-pages 6.03