355 lines
11 KiB
HTML
355 lines
11 KiB
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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>Qp0zDumpTargetStack()--Dump Formatted Stack Trace Data of the Target
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Thread</title>
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<!-- Begin Header Records ========================================== -->
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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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<!-- Change History: -->
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<!-- YYMMDD USERID Change description -->
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<!-- Direct1 SCRIPT J converted by B2H R4.1 (346) (CMS) by V2KEA304 -->
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<!-- at RCHVMW2 on 17 Feb 1999 at 11:05:09 -->
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<!-- Edited by Kersten Feb 02 -->
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<!-- This file has undergone html cleanup May 2002 by JET -->
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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 type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<a name="Top_Of_Page"></a>
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<h2>Qp0zDumpTargetStack()--Dump Formatted Stack Trace Data of the Target
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Thread</h2>
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<div class="box" style="width: 60%;">
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<br>
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Syntax<br>
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<pre>
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#include <qp0ztrc.h>
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int Qp0zDumpTargetStack(int <em>handle</em>,
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const char <em>*label</em>);
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</pre>
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<br>
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Service Program Name: QP0ZCPA<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: Conditional; see <a href="#USAGE_NOTES">Usage Notes</a>.<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <strong>Qp0zDumpTargetStack()</strong> function dumps a formatted
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representation of the call stack of the target thread to the user trace. The
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target thread is specified by <em>handle</em>, which can be filled in using the
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<em>pthread_t</em> structure. The formatted call stack is labeled with the text
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string specified by <em>label</em>. The formatted call stack shows the library,
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program, module, and procedure information associated with each frame on the
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call stack at the time the function was called.</p>
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<p>The formatted dump of the target call stack shows the oldest entries first,
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followed by newer entries.</p>
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<p>For consistent results, ensure that the target thread specified in the <em>
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handle</em> parameter is blocked or waiting for some resource and not actively
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running.</p>
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<p>If a target thread that is actively running is specified, the stack trace
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information may be inconsistent.</p>
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<p>An application should not use the tracing function in performance critical
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code. These functions are intended for debugging exception or error conditions.
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The user trace is a permanent user space object named <em>
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QP0Z<jobnumber></em> in the QUSRSYS library. The user trace is created
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the first time any thread in a job writes trace output. See the Change User
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Trace (CHGUSRTRC), Dump User Trace (DMPUSRTRC) and Delete User Trace
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(DLTUSRTRC) CL commands for information about manipulating the user trace
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properties and objects.</p>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong><em>handle</em></strong></dt>
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<dd>(Input) A handle to the target thread.<br>
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<br>
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</dd>
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<dt><strong><em>label</em></strong></dt>
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<dd>(Input) A pointer to a string that is used to label the stack dump.</dd>
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</dl>
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<br>
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<h3>Authorities</h3>
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<p>None.</p>
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<br>
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<h3>Return Value</h3>
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<table cellpadding="5">
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<!-- cols="10 90" -->
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<tr>
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<td align="left" valign="top"><em>0</em></td>
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<td align="left" valign="top"><strong>Qp0zDumpTargetStack()</strong> was
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successful.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>value</em></td>
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<td align="left" valign="top"><strong>Qp0zDumpTargetStack()</strong> was not
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successful. The value returned is an errno indicating the failure.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Error Conditions</h3>
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<p>If <strong>Qp0zDumpTargetStack()</strong> is not successful, the return
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value usually indicates one of the following errors. Under some conditions, the
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return value could indicate an error other than those listed here.</p>
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<dl>
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<dt><em>[EFAULT]</em></dt>
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<dd>
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<p>The address used for an argument is not correct.</p>
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<p>In attempting to use an argument in a call, the system detected an address
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that is not valid.</p>
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<p>While attempting to access a parameter passed to this function, the system
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detected an address that is not valid.</p>
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</dd>
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<dt><em>[ESRCH]</em></dt>
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<dd>
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<p>No item could be found that matches the specified value.</p>
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</dd>
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</dl>
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<br>
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<br>
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<h3><a name="USAGE_NOTES">Usage Notes</a></h3>
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<ol>
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<li>No locks are held on the user trace between calls to the tracing functions.
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The user trace can be deleted while in use. The next function that produces
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trace output will create the user trace again.<br>
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<br>
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</li>
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<li>If another job on the system has the same job number as an existing user
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trace, the existing trace data is cleared, and the trace data from the new job
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replaces it.<br>
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<br>
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</li>
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<li>The <strong>Qp0zDumpTargetStack()</strong> can only safely be used against
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a thread that is stopped or waiting for some activity to occur. If <strong>
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Qp0zDumpTargetStack()</strong> is used with a thread that is actively running,
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the output stack trace may show an inconsistent view of the call stack.<br>
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<br>
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</li>
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<li>If the target thread has more than 128 call stack entries, <strong>
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Qp0zDumpTargetStack()</strong> returns after dumping the first 128 entries of
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the call stack.<br>
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<br>
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</li>
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<li>As the format of the user trace records can change, only the following CL
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commands can be used to manipulate the user trace properties and objects:<br>
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<ul>
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<li>Change User Trace (CHGUSRTRC) can be used to change the characteristics of
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the user trace.<br>
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<br>
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</li>
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<li>Dump User Trace (DMPUSRTRC) can be used to dump trace records to a file or
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to standard output.<br>
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<br>
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</li>
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<li>Delete User Trace (DLTUSRTRC) can be used to delete the user trace
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objects.</li>
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</ul>
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</li>
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</ol>
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<br>
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<h3>Related Information</h3>
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<ul>
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<li><a href="p0zdmp.htm">Qp0zDump()</a>--Dump Formatted Storage Trace Data<br>
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<br>
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</li>
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<li><a href="p0zdmps.htm">Qp0zDumpStack()</a>--Dump Formatted Stack Trace
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Data<br>
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<br>
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</li>
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<li><a href="p0zlog.htm">Qp0zLprintf()</a>--Print Formatted Job Log Data<br>
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<br>
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</li>
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<li><a href="p0zprnt.htm">Qp0zUprintf()</a>--Print Formatted User Trace
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Data</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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<p>The following example uses <strong>Qp0zDumpTargetStack()</strong> and
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<strong>Qp0zUprintf()</strong> functions to produce trace output.</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 <milib.h>
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#include <stdio.h>
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#include <errno.h>
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#include <unistd.h>
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#include <qp0ztrc.h>
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void *threadfunc(void *);
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int main(int argc, char **argv)
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{
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int rc=0;
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pthread_t thread;
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Qp0zUprintf("Entering Testcase\n");
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rc = pthread_create(&thread, NULL, threadfunc, NULL);
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sleep(2); /* Let the thread block */
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/* If the other thread ends or is actively running (that is */
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/* changing the call stack, you may get meaningless results in the*/
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/* stack dump for the target thread.) */
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Qp0zDumpTargetStack(thread.reservedHandle,
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"Dumping target thread's stack\n");
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Qp0zUprintf("Exit with return code of 0\n");
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return 0;
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}
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void foo(void);
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void bar(void);
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void *threadfunc(void *parm)
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{
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Qp0zUprintf("Inside secondary thread\n");
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foo();
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return NULL;
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}
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void foo(void)
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{
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bar();
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}
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void bar(void)
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{
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Qp0zDumpStack("Thread dumping my own stack\n");
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sleep(10); /* Ensure the thread is blocked */
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}
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</pre>
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<br>
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<h3>Trace Output:</h3>
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<p>This trace output was generated after the test case was run by using the CL
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command <strong>DMPUSRTRC JOB(107141/USER/TPZTSTK0) OUTPUT(*STDOUT)</strong>.
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The above example program ran as job 107141/USER/TPZTSTK0.</p>
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<p>Note the following in the trace output:</p>
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<ol>
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<li>Each trace record is indented by several spaces to aid in readability.
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Trace records from different threads have different indentation levels.<br>
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<br>
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</li>
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<li>Each trace record is identified by the hexadecimal thread ID, a colon, and
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a timestamp. The timestamp can be used to aid in debugging of waiting or
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looping threads. For example, the third trace record shown below, (the Entering
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Testcase trace point) was created by thread 0x36, and occurred 0.595584 seconds
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after the last full date and time label. This means that the trace record was
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created on 23 January 1998 at 12:38:10.595584. A full date and time label is
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placed between those trace points that occur during different whole
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seconds.</li>
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</ol>
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<br>
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<br>
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<pre>
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User Trace Dump for job 107141/USER/TPZTSTK0. Size: 300K, Wrapped 0 times.
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--- 01/23/1998 12:38:10 ---
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00000036:595584 Entering Testcase
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00000037:598832 Inside secondary thread
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00000037:599024 Stack Dump For Current Thread
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00000037:599200 Stack: Thread dumping my own stack
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00000037:695440 Stack: Library / Program Module Stmt Procedure
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00000037:752984 Stack: QSYS / QLESPI QLECRTTH 774 : LE_Create_Thread2__FP12crtth_parm_t
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00000037:805664 Stack: QSYS / QP0WPTHR QP0WPTHR 1006 : pthread_create_part2
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00000037:805888 Stack: QP0WTEST / TPZTSTK0 TPZTSTK0 2 : threadfunc
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00000037:806088 Stack: QP0WTEST / TPZTSTK0 TPZTSTK0 1 : foo
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00000037:806288 Stack: QP0WTEST / TPZTSTK0 TPZTSTK0 1 : bar
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00000037:806496 Stack: QSYS / QP0ZCPA QP0ZUDBG 85 : Qp0zDumpStack
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00000037:848280 Stack: QSYS / QP0ZSCPA QP0ZSCPA 274 : Qp0zSUDumpStack
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00000037:848504 Stack: QSYS / QP0ZSCPA QP0ZSCPA 285 : Qp0zSUDumpTargetStack
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00000037:848616 Stack: Completed
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--- 01/23/1998 12:38:12 ---
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00000036:628272 Stack Dump For Target Thread: Handle 7 (0x00000007)
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00000036:628464 Stack: Dumping target thread's stack
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00000036:651608 Stack: Library / Program Module Stmt Procedure
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00000036:651872 Stack: QSYS / QLESPI QLECRTTH 774 : LE_Create_Thread2__FP12crtth_parm_t
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00000036:652088 Stack: QSYS / QP0WPTHR QP0WPTHR 1006 : pthread_create_part2
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00000036:652304 Stack: QP0WTEST / TPZTSTK0 TPZTSTK0 2 : threadfunc
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00000036:652512 Stack: QP0WTEST / TPZTSTK0 TPZTSTK0 1 : foo
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00000036:652712 Stack: QP0WTEST / TPZTSTK0 TPZTSTK0 2 : bar
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00000036:677456 Stack: QSYS / QP0SSRV1 QP0SLIB 1061 : sleep
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00000036:700096 Stack: QSYS / QP0SSRV2 QP0SWAIT 248 : qp0swait__FP13qp0ssigwait_t
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00000036:700216 Stack: Completed
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00000036:700408 Exit with return code of 0
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Press ENTER to end terminal session.
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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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||
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<table cellpadding="2" cellspacing="2">
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||
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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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|
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"unix.htm">UNIX-Type APIs</a> | <a href="aplist.htm">APIs by category</a></td>
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</tr>
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</table>
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||
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</center>
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</body>
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</html>
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