188 lines
4.7 KiB
HTML
188 lines
4.7 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
|
|
<html>
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
|
<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
|
|
<title>pthread_is_multithreaded_np()--Check Current Number of Threads</title>
|
|
<!-- All rights reserved. Licensed Materials Property of IBM -->
|
|
<!-- US Government Users Restricted Rights -->
|
|
<!-- Use, duplication or disclosure restricted by -->
|
|
<!-- GSA ADP Schedule Contract with IBM Corp. -->
|
|
<!-- Begin Header Records ========================================== -->
|
|
<!-- NETMG2 SCRIPT A converted by B2H R4.1 (346) (CMS) by HOLTJM at -->
|
|
<!-- RCHVMW2 on 29 Jan 1999 at 10:01:37 -->
|
|
<!--File Edited November 2001 -->
|
|
<!--End Header Records -->
|
|
<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
|
|
</head>
|
|
<body>
|
|
|
|
<!-- Java sync-link -->
|
|
<script language="Javascript" src="../rzahg/synch.js" type="text/javascript">
|
|
</script>
|
|
|
|
<a name="Top_Of_Page"></a>
|
|
|
|
<h2>pthread_is_multithreaded_np()--Check Current Number of Threads</h2>
|
|
|
|
<div class="box" style="width: 50%;">
|
|
<br>
|
|
Syntax:
|
|
|
|
<pre>
|
|
#include <pthread.h>
|
|
unsigned int pthread_is_multithreaded_np(void);
|
|
</pre>
|
|
Service Program Name: QP0WPTHR<br>
|
|
<!-- iddvc RMBR -->
|
|
<br>
|
|
Default Public Authority: *USE<br>
|
|
<!-- iddvc RMBR -->
|
|
<br>
|
|
Threadsafe: Yes<br>
|
|
<!-- iddvc RMBR -->
|
|
<br>
|
|
Signal Safe: Yes<br>
|
|
<!-- iddvc RMBR -->
|
|
<br>
|
|
</div>
|
|
|
|
<p>The <strong>pthread_is_multithreaded_np</strong>() function returns true or
|
|
false, indicating whether the current process has more than one thread. A
|
|
return value of zero indicates that the calling thread is the only thread in
|
|
the process. A value not equal to zero, indicates that there were multiple
|
|
other threads in the process at the time of the call to
|
|
<strong>pthread_is_multithreaded_np</strong>().</p>
|
|
|
|
<p>The total number of threads currently in the process can be determined by
|
|
adding 1 to the return value of
|
|
<strong>pthread_is_multithreaded_np</strong>().</p>
|
|
|
|
<p><strong>Note:</strong> This function is not portable.</p>
|
|
|
|
<br>
|
|
<h3>Authorities and Locks</h3>
|
|
|
|
<p>None.</p>
|
|
|
|
<br>
|
|
<h3>Parameters</h3>
|
|
|
|
<p>None.</p>
|
|
|
|
<br>
|
|
<h3>Return Value</h3>
|
|
|
|
<dl>
|
|
<dt><strong>0</strong></dt>
|
|
|
|
<dd>No other threads exist in the process.<br><br></dd>
|
|
|
|
<dt><strong>value</strong></dt>
|
|
|
|
<dd>There are currently <em>value+1</em> total threads in the process.</dd>
|
|
</dl>
|
|
|
|
<br>
|
|
<h3>Error Conditions</h3>
|
|
|
|
<p>None.</p>
|
|
|
|
<br>
|
|
<h3>Related Information</h3>
|
|
|
|
<ul>
|
|
<li>The <<strong>pthread.h</strong>> header file. See <a href=
|
|
"rzah4hed.htm">Header files for Pthread functions</a>.<br><br></li>
|
|
|
|
<li><a href="users_99.htm">pthread_is_initialthread_np()</a>--Check if Running in
|
|
the Initial Thread</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 <pthread.h>
|
|
#include <stdio.h>
|
|
#include "check.h"
|
|
|
|
#define NUMTHREADS 3
|
|
|
|
void *threadfunc(void *parm)
|
|
{
|
|
int myHiId;
|
|
int myId;
|
|
pthread_t me = pthread_self();
|
|
|
|
printf("Inside the New Thread\n");
|
|
sleep(2); /* Sleep is not a very robust way to serialize threads */
|
|
return NULL;
|
|
}
|
|
|
|
int main(int argc, char **argv)
|
|
{
|
|
pthread_t thread[NUMTHREADS];
|
|
int rc=0;
|
|
int theHiId=0;
|
|
int theId=0;
|
|
int i=0;
|
|
|
|
printf("Enter Testcase - %s\n", argv[0]);
|
|
|
|
printf("Create %d threads\n", NUMTHREADS);
|
|
|
|
for (i=0; i<NUMTHREADS; ++i) {
|
|
rc = pthread_create(&thread[i], NULL, threadfunc, NULL);
|
|
checkResults("pthread_create()\n", rc);
|
|
printf("Main: Currently %d threads\n",
|
|
pthread_is_multithreaded_np() + 1);
|
|
}
|
|
|
|
printf("Join to threads\n");
|
|
for (i=0; i<NUMTHREADS; ++i) {
|
|
rc = pthread_join(thread[i], NULL);
|
|
checkResults("pthread_join()\n", rc);
|
|
}
|
|
|
|
if (rc = pthread_is_multithreaded_np()) {
|
|
printf("Error: %d Threads still exist!\n", rc+1);
|
|
exit(1);
|
|
}
|
|
printf("Main completed\n");
|
|
return 0;
|
|
}
|
|
</pre>
|
|
|
|
<p><strong>Output:</strong></p>
|
|
|
|
<pre>
|
|
Enter Testcase - QP0WTEST/TPISMT0
|
|
Create 3 threads
|
|
Main: Currently 2 threads
|
|
Main: Currently 3 threads
|
|
Main: Currently 4 threads
|
|
Join to threads
|
|
Inside the New Thread
|
|
Inside the New Thread
|
|
Inside the New Thread
|
|
Main completed
|
|
</pre>
|
|
<br>
|
|
<hr>API introduced: V4R3
|
|
<hr>
|
|
<center>
|
|
<table cellpadding="2" cellspacing="2">
|
|
<tr align="center">
|
|
<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href=
|
|
"rzah4mst.htm">Pthread APIs</a> | <a href="aplist.htm">APIs by
|
|
category</a></td>
|
|
</tr>
|
|
</table>
|
|
</center>
|
|
</body>
|
|
</html>
|
|
|