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281 lines
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML>
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<HEAD>
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<META HTTP-EQUIV="CONTENT-TYPE" CONTENT="text/html; charset=utf-8">
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<TITLE>PTHREAD_ATTR_INIT(3) manual page</TITLE>
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<META NAME="GENERATOR" CONTENT="OpenOffice.org 1.1.3 (Linux)">
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</HEAD>
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<BODY LANG="en-GB" BGCOLOR="#ffffff" DIR="LTR">
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<H4>POSIX Threads for Windows – REFERENCE - <A HREF="http://sources.redhat.com/pthreads-win32">Pthreads-w32</A></H4>
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<P><A HREF="index.html">Reference Index</A></P>
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<P><A HREF="#toc">Table of Contents</A></P>
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<H2><A HREF="#toc0" NAME="sect0">Name</A></H2>
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<P>pthread_attr_init, pthread_attr_destroy,
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pthread_attr_setdetachstate, pthread_attr_getdetachstate,
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pthread_attr_setschedparam, pthread_attr_getschedparam,
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pthread_attr_setschedpolicy, pthread_attr_getschedpolicy,
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pthread_attr_setinheritsched, pthread_attr_getinheritsched,
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pthread_attr_setscope, pthread_attr_getscope - thread creation
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attributes
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</P>
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<H2><A HREF="#toc1" NAME="sect1">Synopsis</A></H2>
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<P><B>#include <pthread.h></B>
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</P>
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<P><B>int pthread_attr_init(pthread_attr_t *</B><I>attr</I><B>);</B>
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</P>
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<P><B>int pthread_attr_destroy(pthread_attr_t *</B><I>attr</I><B>);</B>
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</P>
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<P><B>int pthread_attr_setdetachstate(pthread_attr_t *</B><I>attr</I><B>,
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int </B><I>detachstate</I><B>);</B>
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</P>
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<P><B>int pthread_attr_getdetachstate(const pthread_attr_t *</B><I>attr</I><B>,
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int *</B><I>detachstate</I><B>);</B>
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</P>
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<P><B>int pthread_attr_setschedpolicy(pthread_attr_t *</B><I>attr</I><B>,
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int </B><I>policy</I><B>);</B>
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</P>
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<P><B>int pthread_attr_getschedpolicy(const pthread_attr_t *</B><I>attr</I><B>,
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int *</B><I>policy</I><B>);</B>
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</P>
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<P><B>int pthread_attr_setschedparam(pthread_attr_t *</B><I>attr</I><B>,
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const struct sched_param *</B><I>param</I><B>);</B>
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</P>
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<P><B>int pthread_attr_getschedparam(const pthread_attr_t *</B><I>attr</I><B>,
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struct sched_param *</B><I>param</I><B>);</B>
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</P>
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<P><B>int pthread_attr_setinheritsched(pthread_attr_t *</B><I>attr</I><B>,
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int </B><I>inherit</I><B>);</B>
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</P>
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<P><B>int pthread_attr_getinheritsched(const pthread_attr_t *</B><I>attr</I><B>,
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int *</B><I>inherit</I><B>);</B>
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</P>
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<P><B>int pthread_attr_setscope(pthread_attr_t *</B><I>attr</I><B>,
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int </B><I>scope</I><B>);</B>
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</P>
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<P><B>int pthread_attr_getscope(const pthread_attr_t *</B><I>attr</I><B>,
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int *</B><I>scope</I><B>);</B>
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</P>
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<H2><A HREF="#toc2" NAME="sect2">Description</A></H2>
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<P>Setting attributes for threads is achieved by filling a thread
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attribute object <I>attr</I> of type <B>pthread_attr_t</B>, then
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passing it as second argument to <A HREF="pthread_create.html"><B>pthread_create</B>(3)</A>
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. Passing <B>NULL</B> is equivalent to passing a thread attribute
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object with all attributes set to their default values.
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</P>
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<P><B>pthread_attr_init</B> initializes the thread attribute object
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<I>attr</I> and fills it with default values for the attributes. (The
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default values are listed below for each attribute.)
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</P>
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<P>Each attribute <I>attrname</I> (see below for a list of all
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attributes) can be individually set using the function
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<B>pthread_attr_set</B><I>attrname</I> and retrieved using the
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function <B>pthread_attr_get</B><I>attrname.</I>
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</P>
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<P><B>pthread_attr_destroy</B> destroys a thread attribute object,
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which must not then be reused until it is reinitialized.
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</P>
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<P>Attribute objects are consulted only when creating a new thread.
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The same attribute object can be used for creating several threads.
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Modifying an attribute object after a call to <B>pthread_create</B>
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does not change the attributes of the thread previously created.
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</P>
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<P>The following thread attributes are supported:
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</P>
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<H3><A HREF="#toc3" NAME="sect3">detachstate</A></H3>
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<P>Control whether the thread is created in the joinable state (value
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<B>PTHREAD_CREATE_JOINABLE</B>) or in the detached state (
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<B>PTHREAD_CREATE_DETACHED</B>).
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</P>
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<P>Default value: <B>PTHREAD_CREATE_JOINABLE</B>.
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</P>
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<P>In the joinable state, another thread can synchronize on the
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thread termination and recover its termination code using
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<A HREF="pthread_join.html"><B>pthread_join</B>(3)</A> . When a
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joinable thread terminates, some of the thread resources are kept
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allocated, and released only when another thread performs
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<A HREF="pthread_join.html"><B>pthread_join</B>(3)</A> on that
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thread.
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</P>
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<P>In the detached state, the thread's resources are released
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immediately when it terminates. <A HREF="pthread_join.html"><B>pthread_join</B>(3)</A>
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cannot be used to synchronize on the thread termination.
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</P>
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<P>A thread created in the joinable state can later be put in the
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detached thread using <A HREF="pthread_detach.html"><B>pthread_detach</B>(3)</A>
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.
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</P>
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<H3><A HREF="#toc4" NAME="sect4">schedpolicy</A></H3>
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<P>Select the scheduling policy for the thread: one of <B>SCHED_OTHER</B>
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(regular, non-real-time scheduling), <B>SCHED_RR</B> (real-time,
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round-robin) or <B>SCHED_FIFO</B> (real-time, first-in first-out).
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</P>
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<P><B>Pthreads-w32</B> only supports <B>SCHED_OTHER</B> - attempting
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to set one of the other policies will return an error ENOTSUP.</P>
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<P>Default value: <B>SCHED_OTHER</B>.
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</P>
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<P><B>Pthreads-w32</B> only supports <B>SCHED_OTHER</B> - attempting
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to set one of the other policies will return an error ENOTSUP.</P>
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<P>The scheduling policy of a thread can be changed after creation
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with <A HREF="pthread_setschedparam.html"><B>pthread_setschedparam</B>(3)</A>
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.
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</P>
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<H3><A HREF="#toc5" NAME="sect5">schedparam</A></H3>
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<P>Contain the scheduling parameters (essentially, the scheduling
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priority) for the thread.</P>
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<P><B>Pthreads-w32</B> supports the priority levels defined by the
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Windows system it is running on. Under Windows, thread priorities are
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relative to the process priority class, which must be set via the
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Windows W32 API.</P>
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<P>Default value: priority is 0 (Win32 level <B>THREAD_PRIORITY_NORMAL</B>).
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</P>
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<P>The scheduling priority of a thread can be changed after creation
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with <A HREF="pthread_setschedparam.html"><B>pthread_setschedparam</B>(3)</A>
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.
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</P>
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<H3><A HREF="#toc6" NAME="sect6">inheritsched</A></H3>
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<P>Indicate whether the scheduling policy and scheduling parameters
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for the newly created thread are determined by the values of the
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<I>schedpolicy</I> and <I>schedparam</I> attributes (value
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<B>PTHREAD_EXPLICIT_SCHED</B>) or are inherited from the parent
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thread (value <B>PTHREAD_INHERIT_SCHED</B>).
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</P>
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<P>Default value: <B>PTHREAD_EXPLICIT_SCHED</B>.
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</P>
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<H3><A HREF="#toc7" NAME="sect7">scope</A></H3>
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<P>Define the scheduling contention scope for the created thread. The
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only value supported in the <B>Pthreads-w32</B> implementation is
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<B>PTHREAD_SCOPE_SYSTEM</B>, meaning that the threads contend for CPU
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time with all processes running on the machine. The other value
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specified by the standard, <B>PTHREAD_SCOPE_PROCESS</B>, means that
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scheduling contention occurs only between the threads of the running
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process.</P>
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<P><B>Pthreads-w32</B> only supports <B>PTHREAD_SCOPE_SYSTEM</B>.</P>
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<P>Default value: <B>PTHREAD_SCOPE_SYSTEM</B>.
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</P>
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<H2><A HREF="#toc8" NAME="sect8">Return Value</A></H2>
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<P>All functions return 0 on success and a non-zero error code on
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error. On success, the <B>pthread_attr_get</B><I>attrname</I>
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functions also store the current value of the attribute <I>attrname</I>
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in the location pointed to by their second argument.
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</P>
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<H2><A HREF="#toc9" NAME="sect9">Errors</A></H2>
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<P>The <B>pthread_attr_setdetachstate</B> function returns the
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following error codes on error:
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</P>
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<DL>
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<DL>
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<DT STYLE="margin-right: 1cm; margin-bottom: 0.5cm"><B>EINVAL</B>
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</DT><DD STYLE="margin-right: 1cm; margin-bottom: 0.5cm">
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the specified <I>detachstate</I> is not one of
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<B>PTHREAD_CREATE_JOINABLE</B> or <B>PTHREAD_CREATE_DETACHED</B>.
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</DD></DL>
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</DL>
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<P>
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The <B>pthread_attr_setschedparam</B> function returns the following
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error codes on error:
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</P>
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<DL>
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<DL>
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<DT STYLE="margin-right: 1cm; margin-bottom: 0.5cm"><B>EINVAL</B>
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</DT><DD STYLE="margin-right: 1cm; margin-bottom: 0.5cm">
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the priority specified in <I>param</I> is outside the range of
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allowed priorities for the scheduling policy currently in <I>attr</I>
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(1 to 99 for <B>SCHED_FIFO</B> and <B>SCHED_RR</B>; 0 for
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<B>SCHED_OTHER</B>).
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</DD></DL>
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</DL>
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<P>
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The <B>pthread_attr_setschedpolicy</B> function returns the following
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error codes on error:
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</P>
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<DL>
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<DL>
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<DT STYLE="margin-right: 1cm; margin-bottom: 0.5cm"><B>EINVAL</B>
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</DT><DD STYLE="margin-right: 1cm; margin-bottom: 0.5cm">
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the specified <I>policy</I> is not one of <B>SCHED_OTHER</B>,
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<B>SCHED_FIFO</B>, or <B>SCHED_RR</B>.
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</DD><DT STYLE="margin-right: 1cm; margin-bottom: 0.5cm">
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<B>ENOTSUP</B>
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</DT><DD STYLE="margin-right: 1cm; margin-bottom: 0.5cm">
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<I>policy</I> is not <B>SCHED_OTHER</B>, the only value supported
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by <B>Pthreads-w32</B>.</DD></DL>
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</DL>
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<P>
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The <B>pthread_attr_setinheritsched</B> function returns the
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following error codes on error:
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</P>
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<DL>
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<DL>
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<DT STYLE="margin-right: 1cm; margin-bottom: 0.5cm"><B>EINVAL</B>
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</DT><DD STYLE="margin-right: 1cm; margin-bottom: 0.5cm">
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the specified <I>inherit</I> is not one of <B>PTHREAD_INHERIT_SCHED</B>
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or <B>PTHREAD_EXPLICIT_SCHED</B>.
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</DD></DL>
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</DL>
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<P>
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The <B>pthread_attr_setscope</B> function returns the following error
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codes on error:
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</P>
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<DL>
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<DL>
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<DT STYLE="margin-right: 1cm; margin-bottom: 0.5cm"><B>EINVAL</B>
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</DT><DD STYLE="margin-right: 1cm; margin-bottom: 0.5cm">
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the specified <I>scope</I> is not one of <B>PTHREAD_SCOPE_SYSTEM</B>
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or <B>PTHREAD_SCOPE_PROCESS</B>.
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</DD><DT STYLE="margin-right: 1cm; margin-bottom: 0.5cm">
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<B>ENOTSUP</B>
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</DT><DD STYLE="margin-right: 1cm; margin-bottom: 0.5cm">
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the specified <I>scope</I> is <B>PTHREAD_SCOPE_PROCESS</B> (not
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supported by <B>Pthreads-w32</B>).
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</DD></DL>
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</DL>
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<H2>
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<A HREF="#toc10" NAME="sect10">Author</A></H2>
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<P>Xavier Leroy <Xavier.Leroy@inria.fr>
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</P>
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<P>Modified by Ross Johnson for use with <A HREF="http://sources.redhat.com/pthreads-win32">Pthreads-w32</A>.</P>
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<H2><A HREF="#toc11" NAME="sect11">See Also</A></H2>
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<P><A HREF="pthread_create.html"><B>pthread_create</B>(3)</A> ,
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<A HREF="pthread_join.html"><B>pthread_join</B>(3)</A> ,
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<A HREF="pthread_detach.html"><B>pthread_detach</B>(3)</A> ,
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<A HREF="pthread_setschedparam.html"><B>pthread_setschedparam</B>(3)</A>
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.
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</P>
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<HR>
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<P><A NAME="toc"></A><B>Table of Contents</B></P>
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<UL>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect0" NAME="toc0">Name</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect1" NAME="toc1">Synopsis</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect2" NAME="toc2">Description</A>
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</P>
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<UL>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect3" NAME="toc3">detachstate</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect4" NAME="toc4">schedpolicy</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect5" NAME="toc5">schedparam</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect6" NAME="toc6">inheritsched</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect7" NAME="toc7">scope</A>
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</P>
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</UL>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect8" NAME="toc8">Return
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Value</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect9" NAME="toc9">Errors</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect10" NAME="toc10">Author</A>
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</P>
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<LI><P><A HREF="#sect11" NAME="toc11">See Also</A>
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</P>
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</UL>
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