<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
<html>
|
<!-- Copyright (C) 1988-2021 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." -->
|
<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ -->
|
<head>
|
<title>Debugging with GDB: Thread-Specific Breakpoints</title>
|
|
<meta name="description" content="Debugging with GDB: Thread-Specific Breakpoints">
|
<meta name="keywords" content="Debugging with GDB: Thread-Specific Breakpoints">
|
<meta name="resource-type" content="document">
|
<meta name="distribution" content="global">
|
<meta name="Generator" content="makeinfo">
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
<link href="index.html#Top" rel="start" title="Top">
|
<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
<link href="Thread-Stops.html#Thread-Stops" rel="up" title="Thread Stops">
|
<link href="Interrupted-System-Calls.html#Interrupted-System-Calls" rel="next" title="Interrupted System Calls">
|
<link href="Background-Execution.html#Background-Execution" rel="previous" title="Background Execution">
|
<style type="text/css">
|
<!--
|
a.summary-letter {text-decoration: none}
|
blockquote.smallquotation {font-size: smaller}
|
div.display {margin-left: 3.2em}
|
div.example {margin-left: 3.2em}
|
div.indentedblock {margin-left: 3.2em}
|
div.lisp {margin-left: 3.2em}
|
div.smalldisplay {margin-left: 3.2em}
|
div.smallexample {margin-left: 3.2em}
|
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
|
div.smalllisp {margin-left: 3.2em}
|
kbd {font-style:oblique}
|
pre.display {font-family: inherit}
|
pre.format {font-family: inherit}
|
pre.menu-comment {font-family: serif}
|
pre.menu-preformatted {font-family: serif}
|
pre.smalldisplay {font-family: inherit; font-size: smaller}
|
pre.smallexample {font-size: smaller}
|
pre.smallformat {font-family: inherit; font-size: smaller}
|
pre.smalllisp {font-size: smaller}
|
span.nocodebreak {white-space:nowrap}
|
span.nolinebreak {white-space:nowrap}
|
span.roman {font-family:serif; font-weight:normal}
|
span.sansserif {font-family:sans-serif; font-weight:normal}
|
ul.no-bullet {list-style: none}
|
-->
|
</style>
|
|
|
</head>
|
|
<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
|
<a name="Thread_002dSpecific-Breakpoints"></a>
|
<div class="header">
|
<p>
|
Next: <a href="Interrupted-System-Calls.html#Interrupted-System-Calls" accesskey="n" rel="next">Interrupted System Calls</a>, Previous: <a href="Background-Execution.html#Background-Execution" accesskey="p" rel="previous">Background Execution</a>, Up: <a href="Thread-Stops.html#Thread-Stops" accesskey="u" rel="up">Thread Stops</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
|
</div>
|
<hr>
|
<a name="Thread_002dSpecific-Breakpoints-1"></a>
|
<h4 class="subsection">5.5.4 Thread-Specific Breakpoints</h4>
|
|
<p>When your program has multiple threads (see <a href="Threads.html#Threads">Debugging
|
Programs with Multiple Threads</a>), you can choose whether to set
|
breakpoints on all threads, or on a particular thread.
|
</p>
|
<dl compact="compact">
|
<dd><a name="index-breakpoints-and-threads"></a>
|
<a name="index-thread-breakpoints"></a>
|
<a name="index-break-_2026-thread-thread_002did"></a>
|
</dd>
|
<dt><code>break <var>location</var> thread <var>thread-id</var></code></dt>
|
<dt><code>break <var>location</var> thread <var>thread-id</var> if …</code></dt>
|
<dd><p><var>location</var> specifies source lines; there are several ways of
|
writing them (see <a href="Specify-Location.html#Specify-Location">Specify Location</a>), but the effect is always to
|
specify some source line.
|
</p>
|
<p>Use the qualifier ‘<samp>thread <var>thread-id</var></samp>’ with a breakpoint command
|
to specify that you only want <small>GDB</small> to stop the program when a
|
particular thread reaches this breakpoint. The <var>thread-id</var> specifier
|
is one of the thread identifiers assigned by <small>GDB</small>, shown
|
in the first column of the ‘<samp>info threads</samp>’ display.
|
</p>
|
<p>If you do not specify ‘<samp>thread <var>thread-id</var></samp>’ when you set a
|
breakpoint, the breakpoint applies to <em>all</em> threads of your
|
program.
|
</p>
|
<p>You can use the <code>thread</code> qualifier on conditional breakpoints as
|
well; in this case, place ‘<samp>thread <var>thread-id</var></samp>’ before or
|
after the breakpoint condition, like this:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">(gdb) break frik.c:13 thread 28 if bartab > lim
|
</pre></div>
|
|
</dd>
|
</dl>
|
|
<p>Thread-specific breakpoints are automatically deleted when
|
<small>GDB</small> detects the corresponding thread is no longer in the
|
thread list. For example:
|
</p>
|
<div class="smallexample">
|
<pre class="smallexample">(gdb) c
|
Thread-specific breakpoint 3 deleted - thread 28 no longer in the thread list.
|
</pre></div>
|
|
<p>There are several ways for a thread to disappear, such as a regular
|
thread exit, but also when you detach from the process with the
|
<code>detach</code> command (see <a href="Attach.html#Attach">Debugging an Already-running
|
Process</a>), or if <small>GDB</small> loses the remote connection
|
(see <a href="Remote-Debugging.html#Remote-Debugging">Remote Debugging</a>), etc. Note that with some targets,
|
<small>GDB</small> is only able to detect a thread has exited when the user
|
explictly asks for the thread list with the <code>info threads</code>
|
command.
|
</p>
|
<hr>
|
<div class="header">
|
<p>
|
Next: <a href="Interrupted-System-Calls.html#Interrupted-System-Calls" accesskey="n" rel="next">Interrupted System Calls</a>, Previous: <a href="Background-Execution.html#Background-Execution" accesskey="p" rel="previous">Background Execution</a>, Up: <a href="Thread-Stops.html#Thread-Stops" accesskey="u" rel="up">Thread Stops</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
|
</div>
|
|
|
|
</body>
|
</html>
|
