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pthread_getattr_default_np(3) [linux man page]

PTHREAD_GETATTR_DEFAULT_NP(3)				     Linux Programmer's Manual				     PTHREAD_GETATTR_DEFAULT_NP(3)

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(), | Thread safety | MT-Safe | |pthread_setattr_default_np() | | | +-------------------------------+---------------+---------+ 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 ", stacksize); s = pthread_attr_getguardsize(attr, &guardsize); if (s != 0) errExitEN(s, "pthread_attr_getguardsize"); printf("Guard size: %zd ", guardsize); s = pthread_attr_getschedpolicy(attr, &policy); if (s != 0) errExitEN(s, "pthread_attr_getschedpolicy"); printf("Scheduling policy: %s ", (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 ", schedparam.sched_priority); s = pthread_attr_getdetachstate(attr, &detachstate); if (s != 0) errExitEN(s, "pthread_attr_getdetachstate"); printf("Detach state: %s ", (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 ", (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) Linux 2019-03-06 PTHREAD_GETATTR_DEFAULT_NP(3)

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