105 lines
5.1 KiB
HTML
105 lines
5.1 KiB
HTML
<html lang="en">
|
|
<head>
|
|
<title>In-Process Agent - Debugging with GDB</title>
|
|
<meta http-equiv="Content-Type" content="text/html">
|
|
<meta name="description" content="Debugging with GDB">
|
|
<meta name="generator" content="makeinfo 4.13">
|
|
<link title="Top" rel="start" href="index.html#Top">
|
|
<link rel="prev" href="JIT-Interface.html#JIT-Interface" title="JIT Interface">
|
|
<link rel="next" href="GDB-Bugs.html#GDB-Bugs" title="GDB Bugs">
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
|
<!--
|
|
Copyright (C) 1988-2019 Free Software Foundation, Inc.
|
|
|
|
Permission is granted to copy, distribute and/or modify this document
|
|
under the terms of the GNU Free Documentation License, Version 1.3 or
|
|
any later version published by the Free Software Foundation; with the
|
|
Invariant Sections being ``Free Software'' and ``Free Software Needs
|
|
Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,''
|
|
and with the Back-Cover Texts as in (a) below.
|
|
|
|
(a) The FSF's Back-Cover Text is: ``You are free to copy and modify
|
|
this GNU Manual. Buying copies from GNU Press supports the FSF in
|
|
developing GNU and promoting software freedom.''
|
|
-->
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
|
<style type="text/css"><!--
|
|
pre.display { font-family:inherit }
|
|
pre.format { font-family:inherit }
|
|
pre.smalldisplay { font-family:inherit; font-size:smaller }
|
|
pre.smallformat { font-family:inherit; font-size:smaller }
|
|
pre.smallexample { font-size:smaller }
|
|
pre.smalllisp { font-size:smaller }
|
|
span.sc { font-variant:small-caps }
|
|
span.roman { font-family:serif; font-weight:normal; }
|
|
span.sansserif { font-family:sans-serif; font-weight:normal; }
|
|
--></style>
|
|
</head>
|
|
<body>
|
|
<div class="node">
|
|
<a name="In-Process-Agent"></a>
|
|
<a name="In_002dProcess-Agent"></a>
|
|
<p>
|
|
Next: <a rel="next" accesskey="n" href="GDB-Bugs.html#GDB-Bugs">GDB Bugs</a>,
|
|
Previous: <a rel="previous" accesskey="p" href="JIT-Interface.html#JIT-Interface">JIT Interface</a>,
|
|
Up: <a rel="up" accesskey="u" href="index.html#Top">Top</a>
|
|
<hr>
|
|
</div>
|
|
|
|
<h2 class="chapter">30 In-Process Agent</h2>
|
|
|
|
<p><a name="index-debugging-agent-3161"></a>The traditional debugging model is conceptually low-speed, but works fine,
|
|
because most bugs can be reproduced in debugging-mode execution. However,
|
|
as multi-core or many-core processors are becoming mainstream, and
|
|
multi-threaded programs become more and more popular, there should be more
|
|
and more bugs that only manifest themselves at normal-mode execution, for
|
|
example, thread races, because debugger's interference with the program's
|
|
timing may conceal the bugs. On the other hand, in some applications,
|
|
it is not feasible for the debugger to interrupt the program's execution
|
|
long enough for the developer to learn anything helpful about its behavior.
|
|
If the program's correctness depends on its real-time behavior, delays
|
|
introduced by a debugger might cause the program to fail, even when the
|
|
code itself is correct. It is useful to be able to observe the program's
|
|
behavior without interrupting it.
|
|
|
|
<p>Therefore, traditional debugging model is too intrusive to reproduce
|
|
some bugs. In order to reduce the interference with the program, we can
|
|
reduce the number of operations performed by debugger. The
|
|
<dfn>In-Process Agent</dfn>, a shared library, is running within the same
|
|
process with inferior, and is able to perform some debugging operations
|
|
itself. As a result, debugger is only involved when necessary, and
|
|
performance of debugging can be improved accordingly. Note that
|
|
interference with program can be reduced but can't be removed completely,
|
|
because the in-process agent will still stop or slow down the program.
|
|
|
|
<p>The in-process agent can interpret and execute Agent Expressions
|
|
(see <a href="Agent-Expressions.html#Agent-Expressions">Agent Expressions</a>) during performing debugging operations. The
|
|
agent expressions can be used for different purposes, such as collecting
|
|
data in tracepoints, and condition evaluation in breakpoints.
|
|
|
|
<p><a name="Control-Agent"></a>You can control whether the in-process agent is used as an aid for
|
|
debugging with the following commands:
|
|
|
|
|
|
<a name="index-set-agent-on-3162"></a>
|
|
<dl><dt><code>set agent on</code><dd>Causes the in-process agent to perform some operations on behalf of the
|
|
debugger. Just which operations requested by the user will be done
|
|
by the in-process agent depends on the its capabilities. For example,
|
|
if you request to evaluate breakpoint conditions in the in-process agent,
|
|
and the in-process agent has such capability as well, then breakpoint
|
|
conditions will be evaluated in the in-process agent.
|
|
|
|
<p><a name="index-set-agent-off-3163"></a><br><dt><code>set agent off</code><dd>Disables execution of debugging operations by the in-process agent. All
|
|
of the operations will be performed by <span class="sc">gdb</span>.
|
|
|
|
<p><a name="index-show-agent-3164"></a><br><dt><code>show agent</code><dd>Display the current setting of execution of debugging operations by
|
|
the in-process agent.
|
|
</dl>
|
|
|
|
<ul class="menu">
|
|
<li><a accesskey="1" href="In_002dProcess-Agent-Protocol.html#In_002dProcess-Agent-Protocol">In-Process Agent Protocol</a>
|
|
</ul>
|
|
|
|
</body></html>
|
|
|