249 lines
8.4 KiB
HTML
249 lines
8.4 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_exit()--Terminate Calling Thread</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_exit()--Terminate Calling Thread</h2>
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<div class="box" style="width: 50%;">
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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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void pthread_exit(void *status);
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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_exit</strong>() function terminates the calling thread,
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making its exit <em>status</em> available to any waiting threads. Normally, a
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thread terminates by returning from the start routine that was specified in the
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<strong>pthread_create</strong>() call which started it. An implicit call to
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<strong>pthread_exit</strong>() occurs when any thread returns from its start
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routine. (With the exception of the initial thread, at which time an implicit
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call to <strong>exit</strong>() occurs). The <strong>pthread_exit</strong>()
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function provides an interface similar to <strong>exit</strong>() but on a
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per-thread basis.</p>
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<p>Note that in the i5/OS implementation of threads, the initial thread is
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special. Termination of the initial thread by <strong>pthread_exit</strong>()
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or any thread termination mechanism terminates the entire process.</p>
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<p>The following activities occur in this order when a thread terminates by a
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return from its start routine or <strong>pthread_exit</strong>() or thread
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cancellation:</p>
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<ol>
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<li>Any cancellation cleanup handlers that have been pushed and not popped will
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be executed in reverse order with cancellation disabled.</li>
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<li>Data destructors are called for any thread specific data entries that have
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a non NULL value for both the value and the destructor.</li>
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<li>The thread terminates.</li>
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<li>Thread termination may possibly cause the system to run i5/OS cancel
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handlers (registered with the #pragma cancel_handler directive), or C++
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destructors for automatic objects.</li>
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<li>If thread termination is occurring in the initial thread, it will cause the
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system to terminate all other threads, then run C++ static object destructors,
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activation group cleanup routines and atexit() functions.</li>
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<li>Any mutexes that are held by a thread that terminates, become `abandoned'
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and are no longer valid. Subsequent calls by other threads that attempt to
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acquire the abandoned mutex though <strong>pthread_mutex_lock</strong>() will
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deadlock. Subsequent calls by other threads that attempt to acquire the
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abandoned mutex through <strong>pthread_mutex_trylock</strong>() will return
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<strong>EBUSY</strong>.</li>
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<li>No release of any application visible process resources occur. This
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includes but is not limited to mutexes, file descriptors, or any process level
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cleanup actions.</li>
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</ol>
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<p>Do not call <strong>pthread_exit</strong>() from a cancellation cleanup
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handler or destructor function that was called as a result of either an
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implicit or explicit call to <strong>pthread_exit</strong>(). If
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<strong>pthread_exit</strong>() is called from a cancellation cleanup handler,
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the new invocation of <strong>pthread_exit</strong>() will continue
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cancellation cleanup processing using the next cancellation cleanup handler
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that was pushed. If <strong>pthread_exit</strong>() is called from a data
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destructor, the new invocation of <strong>pthread_exit</strong>() will skip all
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subsequent calls to any data destructors (regardless of the number of
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destructor iterations that have completed), and terminate the thread.</p>
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<p>Cleanup handlers and data destructors are not called when the application
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calls exit() or abort() or otherwise terminates the process. Cleanup handlers
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and data destructors are not called when a thread terminates by any proprietary
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i5/OS mechanism other than the Pthread interfaces.</p>
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<p>The meaning of the <em>status</em> parameter is determined by the
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application except for the following conditions:</p>
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<ol>
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<li>When the thread has been canceled using <strong>pthread_cancel</strong>(),
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the exit status of <strong>PTHREAD_CANCELED</strong> will be made
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available.</li>
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<li>When the thread has been terminated as a result of an unhandled i5/OS
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exception, operator intervention or other proprietary i5/OS mechanism, the
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exit status of <strong>PTHREAD_EXCEPTION_NP</strong> will be made
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available.</li>
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</ol>
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<p>No address error checking is done on the <em>status</em> parameter. Do not
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call <strong>pthread_exit</strong>() with, or return the address of, a variable
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in a threads automatic storage. This storage will be unavailable after the
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thread terminates.</p>
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<p><strong>Note:</strong> If <strong>pthread_exit</strong>() is called by
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application code after step 3 in the above list,
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<strong>pthread_exit</strong>() will fail with the <strong>CPF1F81</strong>
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exception. This indicates that the thread is already considered terminated by
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the system, and <strong>pthread_exit</strong>() cannot continue. If your code
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does not handle this exception, it will appear as if the call to
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<strong>pthread_exit</strong>() was successful.</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>status</strong></dt>
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<dd>(Input) exit status of the thread</dd>
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</dl>
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<br>
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<h3>Return Value</h3>
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<p><strong>pthread_exit</strong>() does not return.</p>
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<br>
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<h3>Error Conditions</h3>
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<p>None.</p>
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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_39.htm">pthread_cancel()</a>--Cancel Thread<br><br></li>
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<li><a href="users_14.htm">pthread_create()</a>--Create Thread<br><br></li>
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<li><a href="users_25.htm#">pthread_join()</a>--Wait for and Detach Thread</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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int theStatus=5;
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void *threadfunc(void *parm)
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{
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printf("Inside secondary thread\n");
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pthread_exit(__VOID(theStatus));
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return __VOID(theStatus); /* Not needed, but this makes the compiler smile */
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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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void *status;
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printf("Enter Testcase - %s\n", argv[0]);
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printf("Create thread using attributes that allow join\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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printf("Wait for the thread to exit\n");
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rc = pthread_join(thread, &status);
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checkResults("pthread_join()\n", rc);
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if (__INT(status) != theStatus) {
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printf("Secondary thread failed\n");
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exit(1);
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}
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printf("Got secondary thread status as expected\n");
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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/TPEXIT0
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Create thread using attributes that allow join
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Wait for the thread to exit
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Inside secondary thread
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Got secondary thread status as expected
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Main completed
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</pre>
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<br>
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<hr>
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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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