This document discusses various tools and techniques for profiling PHP performance, including Xdebug, XHProf, and KCacheGrind. It provides information on setting up and using these tools to detect bottlenecks and optimize code. Specific configuration options are outlined for profiling PHP applications running on Apache, Nginx, and CLI. Metrics like processing time, memory usage, and I/O are identified as important factors to analyze. The goal of profiling is to understand where time is being spent and identify opportunities to improve scalability through code optimizations and server configuration changes.

1. PHP Profiling/performance

2. PHP profiling/perfomance
Processing time,
Transmission time
CPU Bandwith
Memory
I/O

3. PHP profiling/perfomance
• Expected traffic
• Traffic growth
• Scalability means
• Evolutions to come…
Set the context
• Contextually : search engine, file generation,
task…
Establish the objectives

4. PHP profiling/perfomance
•Language
•Framework
•Libraries
•…
Adapt technologies

5. PHP profiling/perfomance
• Smart, structured code
• Lazy loading
• Static variables (singletons/registries)
• Cache
Code
• Autoloader
• Reduce and order include_path
• Client cache (HTTP headers Cache-Control, Expire)
• Avoid regexps
• …
Good practices
• Php.ini : realpath_cache_size
• Nginx : worker_processes, open_file_cache, multi_accept, keepalive, gzip
• Cache op-code
• Disable logs
Server configuration

6. PHP profiling/perfomance
• Ponctual inefficiencies/bottlenecks
detection
• Monitoring (analytics, alert tools)
• Take comparison points (before/after)
• Know when to stop
• Never rely on intuition!
Measure

7. PHP profiling/perfomance
Load tests
• ApacheBenchmark
• Siege
• Httperf
• …
Profiling
• Xdebug
• XHProf
• …
Measuring
tools

8. PHP profiling/perfomance
ApacheBenchmark
ab -n 50 -c 2 -v 1 -p 'post.txt' -T 'application/json'
-H 'Authorization: Bearer eyJ0eXAi.eyJpc3nYXJ.KznbYbc'
'http://api.gma.my/account/authenticate?alt=json&metadata
[foo]=Hello&metadata[bar]=World&metadata[random Val]=Ted'
> bench.txt
{
"application_key":"afaf770",
"email":"ndegardin@tribalnova.com",
"key":"ndegardin«
}
post.txt

9. PHP profiling/perfomance
…
Concurrency Level: 2
Time taken for tests: 25.704 seconds
Complete requests: 50
Failed requests: 44
(Connect: 0, Receive: 0, Length: 44, Exceptions: 0)
Write errors: 0
Non-2xx responses: 50
Total transferred: 2231974 bytes
Total POSTed: 28100
HTML transferred: 2220474 bytes
Requests per second: 1.95 [#/sec] (mean)
Time per request: 1028.176 [ms] (mean)
Time per request: 514.088 [ms] (mean, across all concurrent requests)
Transfer rate: 84.80 [Kbytes/sec] received
1.07 kb/s sent
85.86 kb/s total
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.1 0 0
Processing: 704 1014 154.5 990 1693
Waiting: 704 1014 154.5 990 1693
Total: 705 1015 154.5 990 1693
…
bench.txt

10. PHP profiling/perfomance
• PHP profiling extension
• Developed by Facebook
• The basic version stores traces
• I diddn’t succeed in using the bundled
PHP/HTML app…
• With XHPROF, the profiling is triggered by
calling xhprof_enable(), xhprof_disable()
• Cool solution : auto_append_file,
auto_prepend_file in php.ini
XHProf

11. PHP profiling/perfomance
• Website http://xhprof.io
• Sources https://github.com/gajus/xhprof.io
• Profiling stored in database
• php.ini
• auto_append_file=/var/www/xhprofio/inc/append.php
• auto_prepend_file=/var/www/xhprofio/inc/prepend.php
• Not my recommandation
XHProf.io

12. PHP profiling/perfomance
• Sources https://github.com/sepehr/xhprof
• Profiling stored in database (one table « details »)
• Very good profiler
• php.ini
• auto_prepend_file=/var/www/xhprof/external/header.php
• auto_append_file=/var/www/xhprof/external/footer.php
• In CGI :
• activation by cookie _profile=1
• or by adding the parameter _profile=1 to the URL (adds the cookie,
then redirects)
• In CLI :
• auto_prepend/auto_append in/etc/php5/cli/php.ini
• activation by « export XHPROF_PROFILE=1 »
XHGUI

13. PHP profiling/perfomance
• Activate profiling by vhost in Apache
• Activate profiling by using a nginx/PHP-FPM pool :
/etc/php5/fpm/pool.d/www.conf :
• Activate profiling by vhost in nginx/PHP-FPM, in a
location section
XHProf notes
fastcgi_param PHP_ADMIN_VALUE
"auto_prepend_file=/var/www/xhprof/external/header.phpnauto_append_file=/var/
www/xhprof/external/footer.php";
php_admin_value auto_prepend_file "/var/www/xhprof/external/header.php"
php_admin_value auto_append_file "/var/www/xhprof/external/footer.php"
php_admin_value[auto_prepend_file] = /var/www/xhprofio/inc/prepend.php"
php_admin_value[auto_appendfile] = /var/www/xhprofio/inc/append.php"

14. PHP profiling/perfomance
• Web site http://xdebug.org/
• Developed by Derik Rethans
• PHP extension, now generally bundled with PHP
• Features :
• Debugging functions (time, calls, scream)
• Maximum nesting protection
• Enhanced stacktraces
• Remote debugging
• Profiling
• Code coverage
Xdebug

15. PHP profiling/perfomance
Xdebug notes about debugging
zend_extension=/usr/lib/php5/20090626/xdebug.so
xdebug.remote_enable = 1
xdebug.remote_handler = "dbgp"
xdebug.remote_port = 9000
xdebug.remote_mode = req
xdebug.remote_host = 192.168.56.1
xdebug.profiler_enable = 1
xdebug.profiler_output_dir = /var/log/xdebug
xdebug.profiler_output_name =
cachegrind.out.%H_%s_%R.xt
php.ini

16. PHP profiling/perfomance
• Prevent nginx from sending a gateway timeout (504) :
in /etc/nginx/nginx.conf, add
• Remote debug events triggered externally by setting a
XDEBUG_SESSION cookie and, if needed, mapping
paths (client/server) in your IDE
• Remote debug CLI scripts by running export
XDEBUG_CONFIG="idekey=netbeans-xdebug"and
setting php.ini xdebug.remote_host
Xdebug notes about debugging
fastcgi_read_timeout 3000;
keepalive_timeout 3000;
keepalive_requests 3000;
client_header_timeout 3000;
client_body_timeout 3000;
nginx.conf

17. PHP profiling/perfomance
• The traces are stored as files
• It often weights about 2Mo (be careful when forgetting it)
• Using a fixed name (without timestamp) in php.ini
xdebug.profiler.output_name allows a run script to erase the
previous one
• No official Xdebug trace extension, I suggest
cachegrind.out.[…].xt
• Profilers :
• WinCacheGrind (Windows) : somewhat simple
• WebGrind (Web) : « For quick’n’dirty optimizations it does the
job »
• KCacheGrind (KDE) : the best one
• PHPStorm : not really useful
Xdebug notes about profiling

18. PHP profiling/perfomance
• To run it under Windows, use KDE4Win
(package system similar to Cygwin’s one),
it should be in the « kdesdk » package.
Not available on all mirrors.
• Install GraphViz to enable drawing some
charts (and add its /bin directory the the
PATH)
• Check the Call Graph view!
kCacheGrind

19. PHP profiling/perfomance
• About different times :
• The wall time includes I/O (network latency, database
accesses, waiting for an user input…)
• The including time includes the children call
• The CPU exclusion time (self time in KCacheGrind) is the
more relevant value
• Switch between display formats :
• Percentage is better for comparing values
• Time is better for assessing values
• Tweaking script parameters (input configuration, number
of entries processed in database, number of iterations…)
may allow to observe different phenomena
Notes about profiling

20. Nicolas Degardin
ndegardin@tribalnova.com
Merci !