246 lines
7.1 KiB
HTML
246 lines
7.1 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 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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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>pthread_setschedparam()--Set Target Thread Scheduling Parameters</title>
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<!-- Begin Header Records ========================================== -->
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<!-- NETMG2 SCRIPT A converted by B2H R4.1 (346) (CMS) by HOLTJM at -->
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<!-- RCHVMW2 on 29 Jan 1999 at 10:01:37 -->
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<!--File Edited November 2001 -->
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<!--End Header Records -->
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<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
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</head>
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<body>
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<!-- Java sync-link -->
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<script language="Javascript" src="../rzahg/synch.js" type="text/javascript">
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</script>
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<a name="Top_Of_Page"></a>
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<h2>pthread_setschedparam()--Set Target Thread Scheduling Parameters</h2>
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<div class="box" style="width: 70%;">
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<br>
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Syntax:
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<pre>
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#include <pthread.h>
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#include <sched.h>
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int pthread_setschedparam(pthread_t thread, int policy,
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const struct sched_param *param);
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</pre>
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Service Program Name: QP0WPTHR<br>
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<!-- iddvc RMBR -->
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<br>
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Default Public Authority: *USE<br>
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<!-- iddvc RMBR -->
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<br>
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Threadsafe: Yes<br>
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<!-- iddvc RMBR -->
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<br>
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Signal Safe: No<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <strong>pthread_setschedparam</strong>() function sets the scheduling
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parameters of the target thread. The supported i5/OS scheduling
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<em>policy</em> is <strong>SCHED_OTHER</strong>. An attempt to set the
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<em>policy</em> to a value other than this cause the <strong>EINVAL</strong>
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error. The <em>sched_priority</em> field of the <em>param</em> parameter must
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range from <strong>PRIORITY_MIN</strong> to <strong>PRIORITY_MAX</strong> or
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the <strong>ENOTSUP</strong> error occurs.</p>
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<p>All reserved fields in the scheduling parameters structure must be binary 0
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or the EINVAL error occurs.</p>
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<p><strong>Note:</strong> Do not use <strong>pthread_setschedparam</strong>()
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to set the priority of a thread if you also use another mechanism (outside of
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the pthread APIs) to set the priority of a thread. If you do,
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<strong>pthread_getschedparam</strong>() returns only that information that was
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set by the pthread interfaces (<strong>pthread_setschedparam</strong>() or
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modification of the thread attribute using
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<strong>pthread_attr_setschedparam</strong>()).</p>
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<br>
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<h3>Authorities and Locks</h3>
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<p>None.</p>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong>thread</strong></dt>
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<dd>(Input) Pthread handle of the target thread<br><br></dd>
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<dt><strong>policy</strong></dt>
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<dd>(Input) Scheduling policy (must be <strong>SCHED_OTHER</strong>)<br><br></dd>
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<dt><strong>param</strong></dt>
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<dd>(Input) Scheduling parameters</dd>
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</dl>
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<br>
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<h3>Return Value</h3>
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<dl>
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<dt><strong>0</strong></dt>
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<dd><strong>pthread_setschedparam</strong>() was successful.<br><br></dd>
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<dt><strong>value</strong></dt>
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<dd><strong>pthread_setschedparam</strong>() was not successful. <em>value</em>
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is set to indicate the error condition.</dd>
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</dl>
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<br>
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<h3>Error Conditions</h3>
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<p>If <strong>pthread_setschedparam</strong>() was not successful, the error
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condition returned usually indicates one of the following errors. Under some
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conditions, the value returned could indicate an error other than those listed
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here.</p>
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<dl>
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<dt><em>[EINVAL]</em></dt>
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<dd><p>The value specified for the argument is not correct.</p></dd>
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<dt><em>[ENOTSUP]</em></dt>
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<dd><p>The value specified for the priority argument is not supported.</p></dd>
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</dl>
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<br>
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<h3>Related Information</h3>
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<ul>
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<li>The <<strong>pthread.h</strong>> header file. See <a href=
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"rzah4hed.htm">Header files for Pthread functions</a>.<br><br></li>
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<li><a href="users_21.htm">pthread_getschedparam()</a>--Get Thread Scheduling
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Parameters</li>
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</ul>
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<br>
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<h3>Example</h3>
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<p>See <a href="../apiref/aboutapis.htm#codedisclaimer">Code disclaimer information</a>
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for information pertaining to code examples.</p>
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<pre>
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#define _MULTI_THREADED
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#include <pthread.h>
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#include <sched.h>
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#include <stdio.h>
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#include "check.h"
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#define BUMP_PRIO 1
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int thePriority = 0;
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int showSchedParam(pthread_t thread)
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{
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struct sched_param param;
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int policy;
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int rc;
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printf("Get scheduling parameters\n");
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rc = pthread_getschedparam(thread, &policy, &param);
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checkResults("pthread_getschedparam()\n", rc);
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printf("The thread scheduling parameters indicate:\n"
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"priority = %d\n", param.sched_priority);
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return param.sched_priority;
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}
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void *threadfunc(void *parm)
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{
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int rc;
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printf("Inside secondary thread\n");
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thePriority = showSchedParam(pthread_self());
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sleep(5); /* Sleep is not a very robust way to serialize threads */
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return NULL;
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}
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int main(int argc, char **argv)
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{
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pthread_t thread;
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int rc=0;
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struct sched_param param;
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int policy = SCHED_OTHER;
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int theChangedPriority=0;
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printf("Enter Testcase - %s\n", argv[0]);
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printf("Create thread using default attributes\n");
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rc = pthread_create(&thread, NULL, threadfunc, NULL);
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checkResults("pthread_create()\n", rc);
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sleep(2); /* Sleep is not a very robust way to serialize threads */
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memset(&param, 0, sizeof(param));
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/* Bump the priority of the thread a small amount */
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if (thePriority - BUMP_PRIO >= PRIORITY_MIN_NP) {
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param.sched_priority = thePriority - BUMP_PRIO;
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}
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printf("Set scheduling parameters, prio=%d\n",
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param.sched_priority);
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rc = pthread_setschedparam(thread, policy, &param);
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checkResults("pthread_setschedparam()\n", rc);
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/* Let the thread fill in its own last priority */
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theChangedPriority = showSchedParam(thread);
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if (thePriority == theChangedPriority ||
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param.sched_priority != theChangedPriority) {
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printf("The thread did not get priority set correctly, "
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"first=%d last=%d expected=%d\n",
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thePriority, theChangedPriority, param.sched_priority);
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exit(1);
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}
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sleep(5); /* Sleep is not a very robust way to serialize threads */
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printf("Main completed\n");
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return 0;
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}
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</pre>
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<p><strong>Output:</strong></p>
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<pre>
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Enter Testcase - QP0WTEST/TPSSP0
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Create thread using default attributes
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Inside secondary thread
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Get scheduling parameters
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The thread scheduling parameters indicate:
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priority = 0
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Set scheduling parameters, prio=-1
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Get scheduling parameters
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The thread scheduling parameters indicate:
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priority = -1
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Main completed
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</pre>
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<br>
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<hr>API introduced: V4R3
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<hr>
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<center>
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<table cellpadding="2" cellspacing="2">
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<tr align="center">
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<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href=
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"rzah4mst.htm">Pthread APIs</a> | <a href="aplist.htm">APIs by
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category</a></td>
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</tr>
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</table>
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</center>
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</body>
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</html>
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