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 <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="prev">Background Execution</a>, Up: <a href="Thread-Stops.html#Thread-Stops" accesskey="u" rel="up">Thread Stops</a> &nbsp; [<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-threadno"></a>
 </dd>
 <dt><code>break <var>linespec</var> thread <var>threadno</var></code></dt>
 <dt><code>break <var>linespec</var> thread <var>threadno</var> if &hellip;</code></dt>
 <dd><p><var>linespec</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 &lsquo;<samp>thread <var>threadno</var></samp>&rsquo; 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>threadno</var> specifier
 is one of the numeric thread identifiers assigned by <small>GDB</small>, shown
 in the first column of the &lsquo;<samp>info threads</samp>&rsquo; display.
 </p>
 <p>If you do not specify &lsquo;<samp>thread <var>threadno</var></samp>&rsquo; 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 &lsquo;<samp>thread <var>threadno</var></samp>&rsquo; before or
 after the breakpoint condition, like this:
 </p>
 <div class="smallexample">
 <pre class="smallexample">(gdb) break frik.c:13 thread 28 if bartab &gt; 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">
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 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="prev">Background Execution</a>, Up: <a href="Thread-Stops.html#Thread-Stops" accesskey="u" rel="up">Thread Stops</a> &nbsp; [<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>
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	<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="prev">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-threadno"></a>
	</dd>
	<dt><code>break <var>linespec</var> thread <var>threadno</var></code></dt>
	<dt><code>break <var>linespec</var> thread <var>threadno</var> if …</code></dt>
	<dd><p><var>linespec</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>threadno</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>threadno</var> specifier
	is one of the numeric 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>threadno</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>threadno</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="prev">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>
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