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<H1>PTHREAD_GETATTR_DEFAULT_NP</H1>
Section: Linux Programmer's Manual (3)<BR>Updated: 2019-03-06<BR><A HREF="#index">Index</A>
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
<A NAME="lbAB">&nbsp;</A>
<H2>NAME</H2>
pthread_getattr_default_np, pthread_setattr_default_np, -
get or set default thread-creation attributes
<A NAME="lbAC">&nbsp;</A>
<H2>SYNOPSIS</H2>
<PRE>
<B>#define _GNU_SOURCE</B> /* See <A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A>(7) */
<B>#include &lt;<A HREF="file:///usr/include/pthread.h">pthread.h</A>&gt;</B>
<B>int pthread_getattr_default_np(pthread_attr_t *</B><I>attr</I><B>);</B>
<B>int pthread_setattr_default_np(pthread_attr_t *</B><I>attr</I><B>);</B>
Compile and link with <I>-pthread</I>.
</PRE>
<A NAME="lbAD">&nbsp;</A>
<H2>DESCRIPTION</H2>
The
<B>pthread_setattr_default_np</B>()
function sets the default attributes used for creation of a new
thread---that is, the attributes that are used when
<B><A HREF="/cgi-bin/man/man2html?3+pthread_create">pthread_create</A></B>(3)
is called with a second argument that is NULL.
The default attributes are set using the attributes supplied in
<I>*attr</I>,
a previously initialized thread attributes object.
Note the following details about the supplied attributes object:
<DL COMPACT>
<DT id="1">*<DD>
The attribute settings in the object must be valid.
<DT id="2">*<DD>
The
<I>stack address</I>
attribute must not be set in the object.
<DT id="3">*<DD>
Setting the
<I>stack size</I>
attribute to zero means leave the default stack size unchanged.
</DL>
<P>
The
<B>pthread_getattr_default_np</B>()
function initializes the thread attributes object referred to by
<I>attr</I>
so that it contains the default attributes used for thread creation.
<A NAME="lbAE">&nbsp;</A>
<H2>ERRORS</H2>
<DL COMPACT>
<DT id="4"><B>EINVAL</B>
<DD>
(<B>pthread_setattr_default_np</B>())
One of the attribute settings in
<I>attr</I>
is invalid, or the stack address attribute is set in
<I>attr</I>.
<DT id="5"><B>ENOMEM</B>
<DD>
(<B>pthread_setattr_default_np</B>())
Insufficient memory.
</DL>
<A NAME="lbAF">&nbsp;</A>
<H2>VERSIONS</H2>
These functions are available in glibc since version 2.18.
<A NAME="lbAG">&nbsp;</A>
<H2>ATTRIBUTES</H2>
For an explanation of the terms used in this section, see
<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
<TABLE BORDER>
<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
<TR VALIGN=top><TD>
<B>pthread_getattr_default_np</B>(),
<B>pthread_setattr_default_np</B>()
</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
</TABLE>
<A NAME="lbAH">&nbsp;</A>
<H2>CONFORMING TO</H2>
These functions are nonstandard GNU extensions;
hence the suffix &quot;_np&quot; (nonportable) in their names.
<A NAME="lbAI">&nbsp;</A>
<H2>EXAMPLE</H2>
The program below uses
<B>pthread_getattr_default_np</B>()
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:
<P>
$ <B>./a.out</B>
Stack size: 8388608
Guard size: 4096
Scheduling policy: SCHED_OTHER
Scheduling priority: 0
Detach state: JOINABLE
Inherit scheduler: INHERIT
<P>
<A NAME="lbAJ">&nbsp;</A>
<H3>Program source</H3>
#define _GNU_SOURCE
#include &lt;<A HREF="file:///usr/include/pthread.h">pthread.h</A>&gt;
#include &lt;<A HREF="file:///usr/include/stdio.h">stdio.h</A>&gt;
#include &lt;<A HREF="file:///usr/include/stdlib.h">stdlib.h</A>&gt;
#include &lt;<A HREF="file:///usr/include/errno.h">errno.h</A>&gt;
<P>
#define errExitEN(en, msg) \
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;do&nbsp;{&nbsp;errno&nbsp;=&nbsp;en;&nbsp;perror(msg);&nbsp;\
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;exit(EXIT_FAILURE);&nbsp;}&nbsp;while&nbsp;(0)
<P>
static void
display_pthread_attr(pthread_attr_t *attr)
{
<BR>&nbsp;&nbsp;&nbsp;&nbsp;int&nbsp;s;
<BR>&nbsp;&nbsp;&nbsp;&nbsp;size_t&nbsp;stacksize;
<BR>&nbsp;&nbsp;&nbsp;&nbsp;size_t&nbsp;guardsize;
<BR>&nbsp;&nbsp;&nbsp;&nbsp;int&nbsp;policy;
<BR>&nbsp;&nbsp;&nbsp;&nbsp;struct&nbsp;sched_param&nbsp;schedparam;
<BR>&nbsp;&nbsp;&nbsp;&nbsp;int&nbsp;detachstate;
<BR>&nbsp;&nbsp;&nbsp;&nbsp;int&nbsp;inheritsched;
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;s&nbsp;=&nbsp;pthread_attr_getstacksize(attr,&nbsp;&amp;stacksize);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(s&nbsp;!=&nbsp;0)
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;errExitEN(s,&nbsp;&quot;pthread_attr_getstacksize&quot;);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;printf(&quot;Stack&nbsp;size:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;%zd\n&quot;,&nbsp;stacksize);
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;s&nbsp;=&nbsp;pthread_attr_getguardsize(attr,&nbsp;&amp;guardsize);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(s&nbsp;!=&nbsp;0)
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;errExitEN(s,&nbsp;&quot;pthread_attr_getguardsize&quot;);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;printf(&quot;Guard&nbsp;size:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;%zd\n&quot;,&nbsp;guardsize);
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;s&nbsp;=&nbsp;pthread_attr_getschedpolicy(attr,&nbsp;&amp;policy);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(s&nbsp;!=&nbsp;0)
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;errExitEN(s,&nbsp;&quot;pthread_attr_getschedpolicy&quot;);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;printf(&quot;Scheduling&nbsp;policy:&nbsp;&nbsp;&nbsp;%s\n&quot;,
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(policy&nbsp;==&nbsp;SCHED_FIFO)&nbsp;?&nbsp;&quot;SCHED_FIFO&quot;&nbsp;:
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(policy&nbsp;==&nbsp;SCHED_RR)&nbsp;?&nbsp;&quot;SCHED_RR&quot;&nbsp;:
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(policy&nbsp;==&nbsp;SCHED_OTHER)&nbsp;?&nbsp;&quot;SCHED_OTHER&quot;&nbsp;:&nbsp;&quot;[unknown]&quot;);
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;s&nbsp;=&nbsp;pthread_attr_getschedparam(attr,&nbsp;&amp;schedparam);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(s&nbsp;!=&nbsp;0)
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;errExitEN(s,&nbsp;&quot;pthread_attr_getschedparam&quot;);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;printf(&quot;Scheduling&nbsp;priority:&nbsp;%d\n&quot;,&nbsp;schedparam.sched_priority);
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;s&nbsp;=&nbsp;pthread_attr_getdetachstate(attr,&nbsp;&amp;detachstate);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(s&nbsp;!=&nbsp;0)
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;errExitEN(s,&nbsp;&quot;pthread_attr_getdetachstate&quot;);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;printf(&quot;Detach&nbsp;state:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;%s\n&quot;,
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(detachstate&nbsp;==&nbsp;PTHREAD_CREATE_DETACHED)&nbsp;?&nbsp;&quot;DETACHED&quot;&nbsp;:
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(detachstate&nbsp;==&nbsp;PTHREAD_CREATE_JOINABLE)&nbsp;?&nbsp;&quot;JOINABLE&quot;&nbsp;:
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&quot;???&quot;);
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;s&nbsp;=&nbsp;pthread_attr_getinheritsched(attr,&nbsp;&amp;inheritsched);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(s&nbsp;!=&nbsp;0)
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;errExitEN(s,&nbsp;&quot;pthread_attr_getinheritsched&quot;);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;printf(&quot;Inherit&nbsp;scheduler:&nbsp;&nbsp;&nbsp;%s\n&quot;,
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(inheritsched&nbsp;==&nbsp;PTHREAD_INHERIT_SCHED)&nbsp;?&nbsp;&quot;INHERIT&quot;&nbsp;:
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(inheritsched&nbsp;==&nbsp;PTHREAD_EXPLICIT_SCHED)&nbsp;?&nbsp;&quot;EXPLICIT&quot;&nbsp;:
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&quot;???&quot;);
}
<P>
int
main(int argc, char *argv[])
{
<BR>&nbsp;&nbsp;&nbsp;&nbsp;int&nbsp;s;
<BR>&nbsp;&nbsp;&nbsp;&nbsp;pthread_attr_t&nbsp;attr;
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;s&nbsp;=&nbsp;pthread_getattr_default_np(&amp;attr);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(s&nbsp;!=&nbsp;0)
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;errExitEN(s,&nbsp;&quot;pthread_getattr_default_np&quot;);
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;display_pthread_attr(&amp;attr);
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;exit(EXIT_SUCCESS);
}
<A NAME="lbAK">&nbsp;</A>
<H2>SEE ALSO</H2>
<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_getaffinity_np">pthread_attr_getaffinity_np</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_getdetachstate">pthread_attr_getdetachstate</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_getguardsize">pthread_attr_getguardsize</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_getinheritsched">pthread_attr_getinheritsched</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_getschedparam">pthread_attr_getschedparam</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_getschedpolicy">pthread_attr_getschedpolicy</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_getscope">pthread_attr_getscope</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_getstack">pthread_attr_getstack</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_getstackaddr">pthread_attr_getstackaddr</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_getstacksize">pthread_attr_getstacksize</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_init">pthread_attr_init</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+pthread_create">pthread_create</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?7+pthreads">pthreads</A></B>(7)
<A NAME="lbAL">&nbsp;</A>
<H2>COLOPHON</H2>
This page is part of release 5.05 of the Linux
<I>man-pages</I>
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
<P>
<HR>
<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT id="6"><A HREF="#lbAB">NAME</A><DD>
<DT id="7"><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT id="8"><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT id="9"><A HREF="#lbAE">ERRORS</A><DD>
<DT id="10"><A HREF="#lbAF">VERSIONS</A><DD>
<DT id="11"><A HREF="#lbAG">ATTRIBUTES</A><DD>
<DT id="12"><A HREF="#lbAH">CONFORMING TO</A><DD>
<DT id="13"><A HREF="#lbAI">EXAMPLE</A><DD>
<DL>
<DT id="14"><A HREF="#lbAJ">Program source</A><DD>
</DL>
<DT id="15"><A HREF="#lbAK">SEE ALSO</A><DD>
<DT id="16"><A HREF="#lbAL">COLOPHON</A><DD>
</DL>
<HR>
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using the manual pages.<BR>
Time: 00:05:53 GMT, March 31, 2021
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