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<title>pthread_setpthreadoption_np()--Set Pthread Run-Time Option Data</title>
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<h2>pthread_setpthreadoption_np()--Set Pthread Run-Time Option Data</h2>
<div class="box" style="width: 70%;">
<br>
&nbsp;&nbsp;Syntax:
<pre>
#include &lt;pthread.h&gt;
int pthread_setpthreadoption_np(pthread_option_np_t *optionData);
</pre>
&nbsp;&nbsp;Service Program Name: QP0WTCBH<br>
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&nbsp;&nbsp;Default Public Authority: *USE<br>
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&nbsp;&nbsp;Threadsafe: Yes<br>
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&nbsp;&nbsp;Signal Safe: Yes<br>
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<p>The <strong>pthread_setpthreadoption_np</strong>() function sets option data
in the pthread run-time for the process.</p>
<p>Input data is specified uniquely based on the specified <em>optionData</em>.
See the table below for details about input and output. The option field in the
<em>optionData</em> parameter is always required; other fields may be input,
output, or ignored, based on the specific option used.</p>
<p>For all options, every reserved field in the structure represented by
<em>optionData</em> must be binary zero or the <strong>EINVAL</strong> error is
returned. Unless otherwise noted for an option, the <em>target</em> field in
the <em>option</em> parameter is always ignored, and the contents of the
<em>optionData</em> structure is not changed by the
<strong>pthread_setpthreadoption_np</strong>() function.</p>
<p>The currently supported options, the data they represent, and the valid
operations are as follows:</p>
<table border width="80%" cellpadding="5">
<tr>
<th valign="top"><em>option</em> field of the <em>option</em> parameter</th>
<th valign="top">Description</th>
</tr>
<tr>
<td align="left" valign="top" width="50%">
<strong>PTHREAD_OPTION_POOL_NP</strong></td>
<td align="left" valign="top" width="50%">When a thread terminates and is
detached or joined to, certain data structures from the pthreads run-time are
maintained in a pool for possible reuse by future threads. This improves
performance for creating threads. Typically, an application should not be
concerned with this storage pool. Use this option to set the current maximum
size of the allowed storage pool. The <em>optionValue</em> field of the
<em>optionData</em> parameter is used to set the current maximum number of
thread structures that will be allowed in the storage pool. By default, the
<em>optionValue</em> field must be a valid integer greater than or equal to
zero, or the <strong>EINVAL</strong> error is returned. The default maximum
size of the storage reuse pool contains enough room for 512 thread
structures.</td>
</tr>
<tr>
<td align="left" valign="top">
<strong>PTHREAD_OPTION_POOL_CURRENT_NP</strong></td>
<td align="left" valign="top">If the <em>option</em> field of the
<em>optionData</em> parameter is set to this option, the
<strong>EINVAL</strong> error is returned.</td>
</tr>
<tr>
<td align="left" valign="top">
<strong>PTHREAD_OPTION_THREAD_CAPABLE_NP</strong></td>
<td align="left" valign="top">If the <em>option</em> field of the
<em>optionData</em> parameter is set to this option, the
<strong>EINVAL</strong> error is returned.</td>
</tr>
</table>
<br>
<br>
<h3>Authorities and Locks</h3>
<p>None.</p>
<br>
<h3>Parameters</h3>
<dl>
<dt><strong>option</strong></dt>
<dd>(Input/Output) Address of the variable containing option information and to
contain output option information</dd>
</dl>
<br>
<h3>Return Value</h3>
<dl>
<dt><strong>0</strong></dt>
<dd><strong>pthread_getpthreadoption_np</strong>() was successful.<br><br></dd>
<dt><strong>value</strong></dt>
<dd><strong>pthread_getpthreadoption_np</strong>() was not successful.
<em>value</em> is set to indicate the error condition.</dd>
</dl>
<br>
<h3>Error Conditions</h3>
<p>If <strong>pthread_getpthreadoption_np</strong>() was not successful, the
error condition returned usually indicates one of the following errors. Under
some conditions, the value returned could indicate an error other than those
listed here.</p>
<dl>
<dt><em>[EINVAL]</em></dt>
<dd><p>The value specified for the argument is not correct.</p></dd>
</dl>
<br>
<h3>Related Information</h3>
<ul>
<li>The &lt;<strong>pthread.h</strong>&gt; header file. See <a href=
"rzah4hed.htm">Header files for Pthread functions</a>.<br><br></li>
<li><a href="users_20.htm">pthread_getpthreadoption_np()</a>--Get Pthread Run-Time
Option Data</li>
</ul>
<br>
<h3>Example</h3>
<p>See <a href="../apiref/aboutapis.htm#codedisclaimer">Code disclaimer information</a>
for information pertaining to code examples.</p>
<pre>
#define _MULTI_THREADED
#include &lt;pthread.h&gt;
#include &lt;stdio.h&gt;
#include "check.h"
#define NUMTHREADS 5
void *threadfunc(void *parm)
{
printf("Inside the thread\n");
return NULL;
}
void showCurrentSizeOfPool(void) {
int rc;
pthread_option_np_t opt;
memset(&amp;opt, 0, sizeof(opt));
opt.option = PTHREAD_OPTION_POOL_CURRENT_NP;
rc = pthread_getpthreadoption_np(&amp;opt);
checkResults("pthread_getpthreadoption_np()\n", rc);
printf("Current number of thread structures in pool is %d\n",
opt.optionValue);
return;
}
int main(int argc, char **argv)
{
pthread_t thread[NUMTHREADS];
int rc=0;
int i=0;
pthread_option_np_t opt;
printf("Enter Testcase - %s\n", argv[0]);
printf("Create threads and prime the storage pool\n");
for (i=0; i&lt;NUMTHREADS; ++i) {
rc = pthread_create(&amp;thread[i], NULL, threadfunc, NULL);
checkResults("pthread_create(NULL)\n", rc);
}
printf("Joining all threads at once so thread n does not reuse\n"
"thread n-1's data structures\n");
for (i=0; i&lt;NUMTHREADS; ++i) {
rc = pthread_join(thread[i], NULL);
checkResults("pthread_join()\n", rc);
}
showCurrentSizeOfPool();
/* Set the maximum size of the storage pool to 0. I.e. No reuse of */
/* pthread structures */
printf("Set the max size of the storage pool to 0\n");
memset(&amp;opt, 0, sizeof(opt));
opt.option = PTHREAD_OPTION_POOL_NP;
opt.optionValue = 0;
rc = pthread_setpthreadoption_np(&amp;opt);
checkResults("pthread_setpthreadoption_np()\n", rc);
printf("Create some more threads. Each thread structure will come\n"
"from the storage pool if it exists, but based on the max size of 0,\n"
"the thread structure will not be allowed to be reused\n");
for (i=0; i&lt;NUMTHREADS; ++i) {
rc = pthread_create(&amp;thread[i], NULL, threadfunc, NULL);
checkResults("pthread_create(NULL)\n", rc);
showCurrentSizeOfPool();
rc = pthread_join(thread[i], NULL);
checkResults("pthread_join()\n", rc);
}
printf("Main completed\n");
return 0;
}
</pre>
<p><strong>Output:</strong></p>
<pre>
Enter Testcase - QP0WTEST/TPSEtopT
Create threads and prime the storage pool
Joining all threads at once so thread n does not reuse
thread n-1's data structures
Inside the thread
Inside the thread
Inside the thread
Inside the thread
Inside the thread
Current number of thread structures in pool is 5
Set the max size of the storage pool to 0
Create some more threads. Each thread structure will come
from the storage pool if it exists, but based on the max size of 0,
the thread structure will not be allowed to be reused
Current number of thread structures in pool is 4
Inside the thread
Current number of thread structures in pool is 3
Inside the thread
Current number of thread structures in pool is 2
Inside the thread
Current number of thread structures in pool is 1
Inside the thread
Current number of thread structures in pool is 0
Inside the thread
Main completed
</pre>
<br>
<hr>API introduced: V4R3
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