262 lines
8.2 KiB
HTML
262 lines
8.2 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_getpthreadoption_np()--Get Pthread Run-Time Option Data</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_getpthreadoption_np()--Get Pthread Run-Time Option Data</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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int pthread_getpthreadoption_np(pthread_option_np_t *optionData);
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</pre>
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Service Program Name: QP0WTCBH<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: Yes<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_getpthreadoption_np</strong>() function gets option data
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from the pthread run-time for the process.</p>
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<p>Input and output data is specified and returned uniquely based on the
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specified <em>optionData</em>. See the table below for details about input and
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output. The option field in the <em>optionData</em> parameter is always
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required. Other fields may be input, output, or ignored, based on the specific
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option used.</p>
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<p>For all options, every reserved field in the structure represented by
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<em>optionData</em> must be binary zero or the <strong>EINVAL</strong> error is
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returned. Unless otherwise noted for an option, the <em>target</em> field in
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the <em>option</em> parameter is always ignored.</p>
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<p>The currently supported options, the data they represent, and the valid
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operations are as follows:</p>
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<table border="1" width="80%" cellpadding="5">
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<tr>
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<th><em>option</em> field of the <em>option</em> parameter</th>
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<th>Description</th>
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</tr>
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<tr>
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<td align="left" valign="top" width="50%">
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<strong>PTHREAD_OPTION_POOL_NP</strong></td>
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<td align="left" valign="top" width="50%">When a thread terminates and it is
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detached or joined to, certain data structures from the pthreads run-time are
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maintained in a pool for possible reuse by future threads. This improves
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performance for creating threads. Typically, an application should not be
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concerned with this storage pool. Use this option to determine what the current
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maximum size of the allowed storage pool is. The <em>optionValue</em> field of
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the <em>optionData</em> parameter is set to the current maximum number of
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thread structures, which is maintained in the storage pool. By default, the
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maximum size of the storage reuse pool contains enough room for 512 thread
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structures.</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<strong>PTHREAD_OPTION_POOL_CURRENT_NP</strong></td>
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<td align="left" valign="top">When a thread terminates and it is detached or
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joined to, certain data structures from the pthreads run-time are maintained in
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a pool for possible reuse by future threads. This improves performance for
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creating threads. Typically, an application should not be concerned with this
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storage pool. Use this option to determine how many thread structures are
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currently in the storage pool. The <em>optionValue</em> field of the
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<em>optionData</em> parameter is set to the current number of thread
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structures, which are contained in the storage pool. By default, the storage
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pool contains no thread structures. When a thread terminates and is detached or
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joined to and the current size of the pool is less than the maximum size, the
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thread structure is added to the pool.</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<strong>PTHREAD_OPTION_THREAD_CAPABLE_NP</strong></td>
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<td align="left" valign="top">Not all i5/OS jobs can start threads at all
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times. Use this option to determine whether thread creation is currently
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allowed for your process. The <em>optionValue</em> field of the
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<em>optionData</em> parameter is set to indicate whether thread creation is
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currently allowed. The field is set to 0 to indicate that thread creation is
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not allowed, the field will be set to 1 to indicate thread creation is allowed.
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If thread creation is not allowed, pthread_create() fails with the EBUSY error.
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See pthread_create() for more details.</td>
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</tr>
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</table>
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<br>
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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>option</strong></dt>
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<dd>(Input/Output) Address of the variable containing option information and to
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contain output option information.</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_getpthreadoption_np</strong>() was successful.<br><br></dd>
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<dt><strong>value</strong></dt>
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<dd><strong>pthread_getpthreadoption_np</strong>() was not successful.
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<em>value</em> 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_getpthreadoption_np</strong>() was not successful, the
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error condition returned usually indicates one of the following errors. Under
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some conditions, the value returned could indicate an error other than those
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listed 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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</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_30.htm">pthread_setpthreadoption_np()</a>--Set Pthread Run-Time
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Option Data</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 <stdio.h>
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#include "check.h"
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void *threadfunc(void *parm)
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{
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printf("Inside the thread\n");
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return NULL;
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}
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void showCurrentSizeOfPool(void)
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{
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int rc;
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pthread_option_np_t opt;
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memset(&opt, 0, sizeof(opt));
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opt.option = PTHREAD_OPTION_POOL_CURRENT_NP;
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rc = pthread_getpthreadoption_np(&opt);
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checkResults("pthread_getpthreadoption_np()\n", rc);
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printf("Current number of thread structures in pool is %d\n",
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opt.optionValue);
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return;
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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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pthread_option_np_t opt;
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printf("Enter Testcase - %s\n", argv[0]);
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printf("Create thread using the NULL attributes\n");
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rc = pthread_create(&thread, NULL, threadfunc, NULL);
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checkResults("pthread_create(NULL)\n", rc);
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memset(&opt, 0, sizeof(opt));
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opt.option = PTHREAD_OPTION_POOL_NP;
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rc = pthread_getpthreadoption_np(&opt);
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checkResults("pthread_getpthreadoption_np()\n", rc);
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printf("Current maximum pool size is %d thread structures\n",
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opt.optionValue);
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showCurrentSizeOfPool();
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printf("Joining to the thread may it to the storage pool\n");
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rc = pthread_join(thread, NULL);
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checkResults("pthread_join()\n", rc);
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showCurrentSizeOfPool();
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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/TPGEtopT
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Create thread using the NULL attributes
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Current maximum pool size is 512 thread structures
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Current number of thread structures in pool is 0
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Joining to the thread may it to the storage pool
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Inside the thread
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Current number of thread structures in pool is 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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