97 lines
5.7 KiB
HTML
97 lines
5.7 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="Flight recorders" />
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<meta name="abstract" content="A useful way to debug multithreaded applications is to write data to a flight recorder. A flight recorder is a file, output buffer, or some other object where trace information is written so that problems in the application can be tracked." />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Flight recorders</title>
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</head>
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<body id="rzahwfly-flyco"><a name="rzahwfly-flyco"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Flight recorders</h1>
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<div><p>A useful way to debug multithreaded applications is to write data
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to a flight recorder. A flight recorder is a file, output buffer, or some
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other object where trace information is written so that problems in the application
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can be tracked.</p>
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<div class="section"><p>Entries to and exits from a function are typical information that
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is traced in a flight recorder. Parameters that are passed to functions, major
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changes in control flow, and error conditions are often tracked as well.</p>
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</div>
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<div class="section"><p>The Pthread library provides a way for your application to trace
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problems. Tracing allows you to cut optional trace points, turn the recorder
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on or off, and recompile your application so that all of the tracing code
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is removed.</p>
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</div>
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<div class="section"><p>You can use different levels of tracing. If your application wants
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to honor the trace levels, it is the application's responsibility to cue trace
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points at the appropriate trace levels, or manage the trace level. The Pthread
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library provides APIs, macros, and trace level variables to assist you.</p>
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</div>
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<div class="section"><p>For Pthread tracing, an error-level tracing displays only those
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trace points that have error-level severity. An informational-level tracing
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traces all error-level trace points in addition to the informational trace
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points. A verbose-level trace point traces all levels. Each trace point automatically
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includes the thread ID, a timestamp of millisecond granularity, and the trace
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data.</p>
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</div>
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<div class="section"><p>The CL commands that enable, display, and work with the tracing
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are part of <span class="keyword">i5/OS™</span>. </p>
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</div>
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<div class="section"><p>The tracing buffers for your tracepoints are created as user space
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objects in the QUSRSYS library. The trace buffers are named QP0Zxxxxxx, in
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which xxxxxx is the six-digit job number of the job that performed the tracing. </p>
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</div>
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<div class="section"><p>The following APIs relate to tracing and are detailed in the
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UNIX-Type APIs guide:</p>
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<ul><li><span class="apiname">Qp0zUprintf</span> - print formatted trace data </li>
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<li><span class="apiname">Qp0zDump</span> - dump formatted hexadecimal
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data </li>
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<li><span class="apiname">Qp0zDumpStack</span> - dump the call stack of the calling
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thread</li>
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<li><span class="apiname">Qp0zDumpTargetStack</span> - dump the call stack of the target
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thread</li>
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<li><span class="apiname">Qp0zLprintf</span> - print formatted job log message </li>
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</ul>
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</div>
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<div class="section"><p>The following CL commands that allow you to manipulate tracing:</p>
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<ul><li><span class="cmdname">DMPUSRTRC</span> - dump the contents of a specified job's
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trace </li>
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<li><span class="cmdname">CHGUSRTRC</span> - change attributes (size, wrapping, clear)
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of a specified job's trace</li>
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<li><span class="cmdname">DLTUSRTRC</span> - delete the persistent trace object that
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is associated with a job's trace </li>
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</ul>
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</div>
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</div>
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<div>
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<ul class="ullinks">
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<li class="ulchildlink"><strong><a href="rzahwe20rx.htm">Example: Sample flight recorder output from a Pthread program</a></strong><br />
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This example shows a Pthread program that is using the flight recorder or tracing interfaces that are provided by the system.</li>
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</ul>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzahwbugco.htm" title="Use the concepts and techniques that are described here to learn about debugging and servicing multithreaded jobs:">Debugging and servicing of multithreaded jobs</a></div>
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</div>
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</div>
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</body>
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</html>
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