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pthread_getattr_default_np.3: New page documenting pthread_getattr_default_np(3) and pthread_setattr_default_np(3)
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
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.\" Copyright (c) 2016 Michael Kerrisk <mtk.manpages@gmail.com>
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.TH PTHREAD_GETATTR_DEFAULT_NP 3 2016-08-24 "Linux" "Linux Programmer's Manual"
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.SH NAME
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pthread_getattr_default_np, pthread_setattr_default_np, \-
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get or set default thread-creation attributes
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.SH SYNOPSIS
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.nf
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.BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */"
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.B #include <pthread.h>
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.BI "int pthread_getattr_default_np(pthread_attr_t *" attr );
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.BI "int pthread_setattr_default_np(pthread_attr_t *" attr );
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.sp
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Compile and link with \fI\-pthread\fP.
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.fi
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.SH DESCRIPTION
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The
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.BR pthread_setattr_default_np ()
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function sets the default attributes used for creation of a new
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thread\(emthat is, the attributes that are used when
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.BR pthread_create (3)
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is called with a second argument that is NULL.
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The default attributes are set using the attributes supplied in
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.IR *attr ,
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a previously initialized thread attributes object.
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Note the following details about the supplied attributes object:
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.IP * 3
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The attribute settings in the object must be valid.
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.IP *
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The
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.IR "stack address"
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attribute must not be set in the object.
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.IP *
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Setting the
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.IR "stack size"
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attribute to zero means leave the default stack size unchanged.
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.PP
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The
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.BR pthread_getattr_default_np ()
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function initializes the thread attributes object referred to by
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.I attr
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so that it contains the default attributes used for thread creation.
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.SH ERRORS
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.TP
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.B EINVAL
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.RB ( pthread_setattr_default_np ())
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One of the attribute settings in
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.IR attr
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is invalid, or the stack address attribute is set in
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.IR attr .
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.TP
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.B ENOMEM
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.\" Can happen (but unlikely) while trying to allocate memory for cpuset
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.RB ( pthread_setattr_default_np ())
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Insufficient memory.
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.SH VERSIONS
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These functions are available in glibc since version 2.18.
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.ad l
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.TS
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allbox;
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lbw30 lb lb
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l l l.
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Interface Attribute Value
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T{
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.BR pthread_getattr_default_np (),
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.BR pthread_setattr_default_np ()
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T} Thread safety MT-Safe
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.TE
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.ad
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.SH CONFORMING TO
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These functions are nonstandard GNU extensions;
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hence the suffix "_np" (nonportable) in their names.
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.SH EXAMPLE
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The program below uses
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.BR pthread_getattr_default_np ()
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to fetch the default thread-creation attributes and then displays
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various settings from the returned thread attributes object.
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When running the program, we see the following output:
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.in +4n
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.nf
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$ \fB./a.out\fP
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Stack size: 8388608
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Guard size: 4096
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Scheduling policy: SCHED_OTHER
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Scheduling priority: 0
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Detach state: JOINABLE
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Inherit scheduler: INHERIT
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.fi
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.in
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.SS Program source
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\&
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.nf
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#define _GNU_SOURCE
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <errno.h>
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#define errExitEN(en, msg) \\
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do { errno = en; perror(msg); \\
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exit(EXIT_FAILURE); } while (0)
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static void
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display_pthread_attr(pthread_attr_t *attr)
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{
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int s;
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size_t stacksize;
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size_t guardsize;
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int policy;
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struct sched_param schedparam;
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int detachstate;
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int inheritsched;
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s = pthread_attr_getstacksize(attr, &stacksize);
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if (s != 0)
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errExitEN(s, "pthread_attr_getstacksize");
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printf("Stack size: %zd\\n", stacksize);
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s = pthread_attr_getguardsize(attr, &guardsize);
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if (s != 0)
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errExitEN(s, "pthread_attr_getguardsize");
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printf("Guard size: %zd\\n", guardsize);
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s = pthread_attr_getschedpolicy(attr, &policy);
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if (s != 0)
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errExitEN(s, "pthread_attr_getschedpolicy");
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printf("Scheduling policy: %s\\n",
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(policy == SCHED_FIFO) ? "SCHED_FIFO" :
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(policy == SCHED_RR) ? "SCHED_RR" :
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(policy == SCHED_OTHER) ? "SCHED_OTHER" : "[unknown]");
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s = pthread_attr_getschedparam(attr, &schedparam);
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if (s != 0)
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errExitEN(s, "pthread_attr_getschedparam");
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printf("Scheduling priority: %d\\n", schedparam.sched_priority);
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s = pthread_attr_getdetachstate(attr, &detachstate);
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if (s != 0)
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errExitEN(s, "pthread_attr_getdetachstate");
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printf("Detach state: %s\\n",
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(detachstate == PTHREAD_CREATE_DETACHED) ? "DETACHED" :
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(detachstate == PTHREAD_CREATE_JOINABLE) ? "JOINABLE" :
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"???");
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s = pthread_attr_getinheritsched(attr, &inheritsched);
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if (s != 0)
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errExitEN(s, "pthread_attr_getinheritsched");
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printf("Inherit scheduler: %s\\n",
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(inheritsched == PTHREAD_INHERIT_SCHED) ? "INHERIT" :
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(inheritsched == PTHREAD_EXPLICIT_SCHED) ? "EXPLICIT" :
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"???");
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}
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int
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main(int argc, char *argv[])
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{
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int s;
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pthread_attr_t attr;
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s = pthread_getattr_default_np(&attr);
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if (s != 0)
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errExitEN(s, "pthread_getattr_default_np");
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display_pthread_attr(&attr);
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exit(EXIT_SUCCESS);
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}
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.fi
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.SH SEE ALSO
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.ad l
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.nh
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.BR pthread_attr_getaffinity_np (3),
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.BR pthread_attr_getdetachstate (3),
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.BR pthread_attr_getguardsize (3),
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.BR pthread_attr_getinheritsched (3),
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.BR pthread_attr_getschedparam (3),
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.BR pthread_attr_getschedpolicy (3),
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.BR pthread_attr_getscope (3),
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.BR pthread_attr_getstack (3),
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.BR pthread_attr_getstackaddr (3),
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.BR pthread_attr_getstacksize (3),
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.BR pthread_attr_init (3),
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.BR pthread_create (3),
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.BR pthreads (7)
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