<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>Using PHP and DTrace</title>
</head>
<body><div class="manualnavbar" style="text-align: center;">
<div class="prev" style="text-align: left; float: left;"><a href="features.dtrace.introduction.html">Introduction to PHP and DTrace</a></div>
<div class="next" style="text-align: right; float: right;"><a href="features.dtrace.systemtap.html">Using SystemTap with PHP DTrace Static Probes</a></div>
<div class="up"><a href="features.dtrace.html">DTrace Dynamic Tracing</a></div>
<div class="home"><a href="index.html">PHP Manual</a></div>
</div><hr /><div id="features.dtrace.dtrace" class="sect1">
<h2 class="title">Using PHP and DTrace</h2>
<p class="para">
PHP can be configured with DTrace static probes on platforms that
support DTrace Dynamic Tracing.
</p>
<div class="sect2" id="features.dtrace.install">
<h3 class="title">Configuring PHP for DTrace Static Probes</h3>
<p class="para">
Refer to external platform specific documentation for enabling
operating system DTrace support. For example, on Oracle Linux
boot a UEK3 kernel and do:
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
# modprobe fasttrap<br /># chmod 666 /dev/dtrace/helper</span>
</code></div>
</div>
</div>
</p>
<p class="para">
Instead of using <em>chmod</em>, you could instead use an
ACL package rule to limit device access to a specific user.
</p>
<p class="para">
Build PHP with the <em>--enable-dtrace</em> configuration parameter:
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
# ./configure --enable-dtrace ...<br /># make<br /># make install</span>
</code></div>
</div>
</div>
</p>
<p class="para">
This enables the static probes in core PHP. Any PHP extensions
that provide their own probes should be built separately as shared
extensions.
</p>
</div>
<div class="sect2" id="features.dtrace.static-probes">
<h3 class="title">DTrace Static Probes in Core PHP</h3>
<table class="doctable table">
<caption><strong>The following static probes are available in PHP</strong></caption>
<thead>
<tr>
<th>Probe Name</th>
<th>Probe Description</th>
<th>Probe Arguments</th>
</tr>
</thead>
<tbody class="tbody">
<tr>
<td><em>request-startup</em></td>
<td>Fires when a request starts.</td>
<td>char *<var class="varname"><var class="varname">file</var></var>, char *<var class="varname"><var class="varname">request_uri</var></var>, char *<var class="varname"><var class="varname">request_method</var></var></td>
</tr>
<tr>
<td><em>request-shutdown</em></td>
<td>Fires when a request shutdown.</td>
<td>char *<var class="varname"><var class="varname">file</var></var>, char *<var class="varname"><var class="varname">request_uri</var></var>, char *<var class="varname"><var class="varname">request_method</var></var></td>
</tr>
<tr>
<td><em>compile-file-entry</em></td>
<td>Fires when the compilation of a script starts.</td>
<td>char *<var class="varname"><var class="varname">compile_file</var></var>, char *<var class="varname"><var class="varname">compile_file_translated</var></var></td>
</tr>
<tr>
<td><em>compile-file-return</em></td>
<td>Fires when the compilation of a script finishes.</td>
<td>char *<var class="varname"><var class="varname">compile_file</var></var>, char *<var class="varname"><var class="varname">compile_file_translated</var></var></td>
</tr>
<tr>
<td><em>execute-entry</em></td>
<td>Fires when an opcode array is to be executed. For
example, it fires on function calls, includes, and generator
resumes.</td>
<td>char *<var class="varname"><var class="varname">request_file</var></var>, int <var class="varname"><var class="varname">lineno</var></var></td>
</tr>
<tr>
<td><em>execute-return</em></td>
<td>Fires after execution of an opcode array.</td>
<td>char *<var class="varname"><var class="varname">request_file</var></var>, int <var class="varname"><var class="varname">lineno</var></var></td>
</tr>
<tr>
<td><em>function-entry</em></td>
<td>Fires when the PHP engine enters a PHP function or method call.</td>
<td>char *<var class="varname"><var class="varname">function_name</var></var>, char *<var class="varname"><var class="varname">request_file</var></var>, int <var class="varname"><var class="varname">lineno</var></var>, char *<var class="varname"><var class="varname">classname</var></var>, char *<var class="varname"><var class="varname">scope</var></var></td>
</tr>
<tr>
<td><em>function-return</em></td>
<td>Fires when the PHP engine returns from a PHP function or method call.</td>
<td>char *<var class="varname"><var class="varname">function_name</var></var>, char *<var class="varname"><var class="varname">request_file</var></var>, int <var class="varname"><var class="varname">lineno</var></var>, char *<var class="varname"><var class="varname">classname</var></var>, char *<var class="varname"><var class="varname">scope</var></var></td>
</tr>
<tr>
<td><em>exception-thrown</em></td>
<td>Fires when an exception is thrown.</td>
<td>char *<var class="varname"><var class="varname">classname</var></var></td>
</tr>
<tr>
<td><em>exception-caught</em></td>
<td>Fires when an exception is caught.</td>
<td>char *<var class="varname"><var class="varname">classname</var></var></td>
</tr>
<tr>
<td><em>error</em></td>
<td>Fires when an error occurs, regardless of the <a href="errorfunc.configuration.html#ini.error-reporting" class="link">error_reporting</a> level.</td>
<td>char *<var class="varname"><var class="varname">errormsg</var></var>, char *<var class="varname"><var class="varname">request_file</var></var>, int <var class="varname"><var class="varname">lineno</var></var></td>
</tr>
</tbody>
</table>
<p class="para">
PHP extensions may also have additional static probes.
</p>
</div>
<div class="sect2" id="features.dtrace.list-probes">
<h3 class="title">Listing DTrace Static Probes in PHP</h3>
<p class="para">
To list available probes, start a PHP process and then run:
<div class="informalexample">
<div class="example-contents">
<div class="cdata"><pre>
# dtrace -l
</pre></div>
</div>
</div>
</p>
<p class="para">
The output will be similar to:
<div class="informalexample">
<div class="example-contents">
<div class="cdata"><pre>
ID PROVIDER MODULE FUNCTION NAME
[ . . . ]
4 php15271 php dtrace_compile_file compile-file-entry
5 php15271 php dtrace_compile_file compile-file-return
6 php15271 php zend_error error
7 php15271 php ZEND_CATCH_SPEC_CONST_CV_HANDLER exception-caught
8 php15271 php zend_throw_exception_internal exception-thrown
9 php15271 php dtrace_execute_ex execute-entry
10 php15271 php dtrace_execute_internal execute-entry
11 php15271 php dtrace_execute_ex execute-return
12 php15271 php dtrace_execute_internal execute-return
13 php15271 php dtrace_execute_ex function-entry
14 php15271 php dtrace_execute_ex function-return
15 php15271 php php_request_shutdown request-shutdown
16 php15271 php php_request_startup request-startup
</pre></div>
</div>
</div>
</p>
<p class="para">
The Provider column values consist of <em>php</em> and
the process id of the currently running PHP process.
</p>
<p class="para">
If the Apache web server is running, the module name might be, for
example, <var class="filename">libphp5.so</var>, and there would be
multiple blocks of listings, one per running Apache process.
</p>
<p class="para">
The Function column refers to PHP's internal C implementation
function names where each provider is located.
</p>
<p class="para">
If a PHP process is not running, then no PHP probes will be shown.
</p>
</div>
<div class="sect2" id="features.dtrace.examples">
<h3 class="title">DTrace with PHP Example</h3>
<p class="para">
This example shows the basics of the DTrace D scripting language.
<div class="example" id="example-401">
<p><strong>Example #1 <var class="filename">all_probes.d</var> for tracing all PHP Static Probes with DTrace</strong></p>
<div class="example-contents">
<div class="cdata"><pre>
#!/usr/sbin/dtrace -Zs
#pragma D option quiet
php*:::compile-file-entry
{
printf("PHP compile-file-entry\n");
printf(" compile_file %s\n", copyinstr(arg0));
printf(" compile_file_translated %s\n", copyinstr(arg1));
}
php*:::compile-file-return
{
printf("PHP compile-file-return\n");
printf(" compile_file %s\n", copyinstr(arg0));
printf(" compile_file_translated %s\n", copyinstr(arg1));
}
php*:::error
{
printf("PHP error\n");
printf(" errormsg %s\n", copyinstr(arg0));
printf(" request_file %s\n", copyinstr(arg1));
printf(" lineno %d\n", (int)arg2);
}
php*:::exception-caught
{
printf("PHP exception-caught\n");
printf(" classname %s\n", copyinstr(arg0));
}
php*:::exception-thrown
{
printf("PHP exception-thrown\n");
printf(" classname %s\n", copyinstr(arg0));
}
php*:::execute-entry
{
printf("PHP execute-entry\n");
printf(" request_file %s\n", copyinstr(arg0));
printf(" lineno %d\n", (int)arg1);
}
php*:::execute-return
{
printf("PHP execute-return\n");
printf(" request_file %s\n", copyinstr(arg0));
printf(" lineno %d\n", (int)arg1);
}
php*:::function-entry
{
printf("PHP function-entry\n");
printf(" function_name %s\n", copyinstr(arg0));
printf(" request_file %s\n", copyinstr(arg1));
printf(" lineno %d\n", (int)arg2);
printf(" classname %s\n", copyinstr(arg3));
printf(" scope %s\n", copyinstr(arg4));
}
php*:::function-return
{
printf("PHP function-return\n");
printf(" function_name %s\n", copyinstr(arg0));
printf(" request_file %s\n", copyinstr(arg1));
printf(" lineno %d\n", (int)arg2);
printf(" classname %s\n", copyinstr(arg3));
printf(" scope %s\n", copyinstr(arg4));
}
php*:::request-shutdown
{
printf("PHP request-shutdown\n");
printf(" file %s\n", copyinstr(arg0));
printf(" request_uri %s\n", copyinstr(arg1));
printf(" request_method %s\n", copyinstr(arg2));
}
php*:::request-startup
{
printf("PHP request-startup\n");
printf(" file %s\n", copyinstr(arg0));
printf(" request_uri %s\n", copyinstr(arg1));
printf(" request_method %s\n", copyinstr(arg2));
}
</pre></div>
</div>
</div>
</p>
<p class="para">
This script uses the <em>-Z</em> option to
<var class="filename">dtrace</var>, allowing it to be run when there is no
PHP process executing. If this option were omitted the script
would immediately terminate because it knows none of the probes to
be monitored are in existence.
</p>
<p class="para">
The script traces all core PHP static probe points throughout the
duration of a running PHP script. Run the D script:
<div class="informalexample">
<div class="example-contents">
<div class="cdata"><pre>
# ./all_probes.d
</pre></div>
</div>
</div>
</p>
<p class="para">
Run a PHP script or application. The monitoring D script will
output each probe's arguments as it fires.
</p>
<p class="para">
When monitoring is complete, the D script can be terminated with a
<em>^C</em>.
</p>
<p class="para">
On multi-CPU machines the probe ordering might not appear to be
sequential. This depends on which CPU was processing the probes,
and how threads migrate across CPUs. Displaying probe time stamps
will help reduce confusion, for example:
<div class="informalexample">
<div class="example-contents">
<div class="cdata"><pre>
php*:::function-entry
{
printf("%lld: PHP function-entry ", walltimestamp);
[ . . .]
}
</pre></div>
</div>
</div>
</p>
</div>
<div class="sect2" id="features.dtrace.references">
<h3 class="title">See Also</h3>
<ul class="simplelist">
<li class="member"><a href="oci8.dtrace.html" class="link">OCI8 and DTrace Dynamic Tracing</a></li>
</ul>
</div>
</div><hr /><div class="manualnavbar" style="text-align: center;">
<div class="prev" style="text-align: left; float: left;"><a href="features.dtrace.introduction.html">Introduction to PHP and DTrace</a></div>
<div class="next" style="text-align: right; float: right;"><a href="features.dtrace.systemtap.html">Using SystemTap with PHP DTrace Static Probes</a></div>
<div class="up"><a href="features.dtrace.html">DTrace Dynamic Tracing</a></div>
<div class="home"><a href="index.html">PHP Manual</a></div>
</div></body></html>
