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<title>pthread_join()--Wait for and Detach Thread</title>
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<h2>pthread_join()--Wait for and Detach Thread</h2>
<div class="box" style="width: 60%;">
<br>
&nbsp;&nbsp;Syntax:
<pre>
#include &lt;pthread.h&gt;
int pthread_join(pthread_t thread, void **status);
</pre>
&nbsp;&nbsp;Service Program Name: QP0WPTHR<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: No<br>
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<p>The <strong>pthread_join</strong>() function waits for a thread to
terminate, detaches the thread, then returns the threads exit status.</p>
<p>If the <em>status</em> parameter is <strong>NULL</strong>, the threads exit
status is not returned.</p>
<p>The meaning of the threads exit status (value returned to the
<em>status</em> memory location) is determined by the application, except for
the following conditions:</p>
<ol>
<li>When the thread has been canceled using <strong>pthread_cancel</strong>(),
the exit status of <strong>PTHREAD_CANCELED</strong> is made available.</li>
<li>When the thread has been terminated as a result of an unhandled i5/OS
exception, operator intervention or other proprietary i5/OS mechanism, the
exit status of <strong>PTHREAD_EXCEPTION_NP</strong> is made available.</li>
</ol>
<p>Eventually, you should call <strong>pthread_join</strong>(),
<strong>pthread_detach</strong>() or <strong>pthread_extendedjoin_np</strong>()
without specifying the <em>leaveThreadAllocated</em> option for every thread
that is created joinable (with a detach state of
<strong>PTHREAD_CREATE_JOINABLE</strong>) so that the system can reclaim all
resources associated with the thread. Failure to join to or detach joinable
threads causes memory and other resource leaks until the process ends.</p>
<br>
<h3>Authorities and Locks</h3>
<p>None.</p>
<br>
<h3>Parameters</h3>
<dl>
<dt><strong>thread</strong></dt>
<dd>(Input) Pthread handle to the target thread<br><br></dd>
<dt><strong>status</strong></dt>
<dd>(Output) Address of the variable to receive the thread's exit status</dd>
</dl>
<br>
<h3>Return Value</h3>
<dl>
<dt><strong>0</strong></dt>
<dd><strong>pthread_join</strong>() was successful.<br><br></dd>
<dt><strong>value</strong></dt>
<dd><strong>pthread_join</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_join</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>
<dt><em>[ESRCH]</em></dt>
<dd><p>The thread specified could not be found.</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_16.htm">pthread_detach()</a>--Detach Thread<br><br></li>
<li><a href="users_18.htm">pthread_exit()</a>--Terminate Calling Thread<br><br></li>
<li><a href="users_19.htm">pthread_extendedjoin_np()</a>--Wait for Thread with
Extended Options<br><br></li>
<li><a href="users_26.htm">pthread_join_np()</a>--Wait for Thread to End</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"
int okStatus = 34;
void *threadfunc(void *parm)
{
printf("Inside secondary thread\n");
return __VOID(okStatus);
}
int main(int argc, char **argv)
{
pthread_t thread;
int rc=0;
void *status;
printf("Enter Testcase - %s\n", argv[0]);
printf("Create thread using attributes that allow join\n");
rc = pthread_create(&amp;thread, NULL, threadfunc, NULL);
checkResults("pthread_create()\n", rc);
printf("Wait for the thread to exit\n");
rc = pthread_join(thread, &amp;status);
checkResults("pthread_join()\n", rc);
if (__INT(status) != okStatus) {
printf("Secondary thread failed\n");
exit(1);
}
printf("Got secondary thread status as expected\n");
printf("Main completed\n");
return 0;
}
</pre>
<p><strong>Output:</strong></p>
<pre>
Enter Testcase - QP0WTEST/TPJOIN0
Create thread using attributes that allow join
Wait for the thread to exit
Inside secondary thread
Got secondary thread status as expected
Main completed
</pre>
<br>
<hr>API introduced: V4R3
<hr>
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