APD is the Advanced PHP Debugger. It was written to provide profiling and
debugging capabilities for PHP code, as well as to provide the ability to
print out a full stack backtrace. APD supports interactive debugging, but
by default it writes data to trace files. It also offers event based
logging so that varying levels of information (including function calls,
arguments passed, timings, etc.) can be turned on or off for individual
APD is a Zend Extension, modifying the way the internals of PHP handle
function calls, and thus may or may not be compatible with other Zend
Extensions (for example Zend Optimizer).
APD is currently available as a PECL extension from
Make sure you have installed the CGI version of PHP and it is available
in your current path along with the phpize script.
Run the following command to download, build, and install the latest stable
version of APD:
pear install apd
This automatically installs the APD Zend module into your PHP
extensions directory. It is not mandatory to keep it there; you can
store the module in any directory PHP can read as long as you set
the zend_extension parameter accordingly.
To build APD under Windows you need a working PHP compilation
environment as described on http://php.net/ -- basically, it requires
you to have Microsoft Visual C++, win32build.zip, bison/flex, and some know how
to get it to work. Also ensure that adp.dsp has DOS line endings; if it has unix
line endings, Microsoft Visual C++ will complain about it.
As the first line of your PHP script, call the apd_set_pprof_trace() function
to start the trace:
You can insert the line anywhere in your script, but if you do not start
tracing at the beginning of your script you discard profile data that might
otherwise lead you to a performance bottleneck.
Now run your script. The dump output will be written to
If you're running the CGI version of PHP, you will need to add the '-e'
flag to enable extended information for apd to work properly. For
php -e -f script.php
To display formatted profile data, issue the pprofp
command with the sort and display options of your choice. The formatted
output will look something like:
bash-2.05b$ pprofp -R /tmp/pprof.22141.0
Trace for /home/dan/testapd.php
Total Elapsed Time = 0.00
Total System Time = 0.00
Total User Time= 0.00
Real UserSystem secs/cumm
%Time (excl/cumm) (excl/cumm) (excl/cumm) Callscalls/call Memory Usage Name
100.0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.0000 0.00090 main
56.9 0.00 0.00 0.00 0.00 0.00 0.00 1 0.0005 0.00050 apd_set_pprof_trace
28.0 0.00 0.00 0.00 0.00 0.00 0.0010 0.0000 0.00000 preg_replace
14.3 0.00 0.00 0.00 0.00 0.00 0.0010 0.0000 0.00000 str_replace
The -R option used in this example sorts the profile table by the amount
of real time the script spent executing a given function. The "cumm call"
column reveals how many times each function was called, and the "s/call"
column reveals how many seconds each call to the function required, on
To generate a calltree file that you can import into the KCacheGrind
profile analysis application, issue the pprof2calltree