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<title>pthread_cleanup_pop()--Pop Cleanup Handler off of Cancellation Cleanup
Stack</title>
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<h2>pthread_cleanup_pop()--Pop Cleanup Handler off of Cancellation Cleanup
Stack</h2>
<div class="box" style="width: 50%;">
<br>
&nbsp;&nbsp;Syntax:
<pre>
#include &lt;pthread.h&gt;
void pthread_cleanup_pop(int execute);
</pre>
&nbsp;&nbsp;Service Program Name: QP0WPTHR<br>
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<br>
&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_cleanup_pop</strong>() function pops the last cleanup
handler from the cancellation cleanup stack. If the <em>execute</em> parameter
is nonzero, the handler is called with the argument specified by the <strong>
pthread_cleanup_push</strong>() call with which the handler was registered.</p>
<p>The <strong>pthread_cleanup_push</strong>() and the matching <strong>
pthread_cleanup_pop</strong>() call should be in the same lexical scope (that is,
same level of brackets {}).</p>
<p>When the thread calls <strong>pthread_exit</strong>() or is cancelled by
<strong>pthread_cancel</strong>(), the cancellation cleanup handlers are called
with the argument specified by the <strong>pthread_cleanup_push</strong>() call
that the handler was registered with.</p>
<p>During this thread cancellation cleanup, the thread calls cancellation
cleanup handlers with cancellation disabled until the last cancellation cleanup
handler returns. The handlers are called in Last In, First Out (LIFO) order.
Automatic storage for the invocation stack frame of the function that
registered the handler is still present when the cancellation cleanup handler
is executed.</p>
<p>When a cancellation cleanup handler is called because of a call to <strong>
pthread_cleanup_pop</strong>(1), the cancellation cleanup handler does not
necessarily run with cancellation disabled. The cancellation state and
cancellation type are not changed by a call to <strong>
pthread_cleanup_pop</strong>(1).</p>
<p>A cancellation cleanup handler should not exit using <strong>
longjmp</strong>() or <strong>siglongjmp</strong>(). If a cleanup handler takes
an exception, the exception condition is handled and ignored and processing
continues. You can look in the job log of the job to see exception messages
generated by cancellation cleanup handlers.</p>
<br>
<h3>Authorities and Locks</h3>
<p>None.</p>
<br>
<h3>Parameters</h3>
<dl>
<dt><strong>execute</strong></dt>
<dd>(Input) Boolean value indicating whether the cancellation cleanup handler
should be executed</dd>
</dl>
<br>
<h3>Return Value</h3>
<p>None.</p>
<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_39.htm">pthread_cancel()</a>--Cancel Thread<br><br></li>
<li><a href="users_42.htm">pthread_cleanup_push()</a>--Push Cleanup Handler onto
Cancellation Cleanup Stack<br><br></li>
<li><a href="users_18.htm">pthread_exit()</a>--Terminate Calling 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 &lt;pthread.h&gt;
#include &lt;stdio.h&gt;
#include "check.h"
void cleanupHandler(void *arg)
{
printf("In the cleanup handler\n");
}
void *threadfunc(void *parm)
{
printf("Entered secondary thread, you should see the cleanup handler\n");
pthread_cleanup_push(cleanupHandler, NULL);
sleep(1); /* Simulate more code here */
pthread_cleanup_pop(1);
return NULL;
}
int main(int argc, char **argv)
{
pthread_t thread;
int rc=0;
printf("Enter Testcase - %s\n", argv[0]);
/* Create a thread using default attributes */
printf("Create thread using the NULL attributes\n");
rc = pthread_create(&amp;thread, NULL, threadfunc, NULL);
checkResults("pthread_create(NULL)\n", rc);
/* sleep() is not a very robust way to wait for the thread */
sleep(5);
printf("Main completed\n");
return 0;
}
</pre>
<p><strong>Output:</strong></p>
<pre>
Enter Testcase - QP0WTEST/TPCLPO0
Create thread using the NULL attributes
Entered secondary thread, you should see the cleanup handler
In the cleanup handler
Main completed
</pre>
<hr>
API introduced: V4R3
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