pthread_setattr_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 (), pthread_setattr_default_np () Thread safety MT-Safe

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\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", (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\n", (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)

Information

Source
Linux kernel
OS/version
Linux
Source updated
September 15, 2017
Page created
February 9, 2018
Page generated
December 2, 2018