CACHING FOR CASH -
BENCHMARKING
Scott MacVicar + Helgi Þormar Þorbjörnsson
php|works 2008

GOALS
Learn how to find slow pages
Locate slow blocks of code
Apply minor optimisations

THOUGHT STEPS
Things seem a bit slow
Take a guess whats slow
Browse lots of code

SYSTEM COMPONENTS
Appliation Server
Database Server
Application
Database
Network

PAGE BENCHMARKING
Single Request doesn’t matter
Average time for maximum amount of users
Hopefully at worst it scales linearly

REQUIREMENTS
Same hardware configuration
Same server configuration
Same network interface speed (100mbps)
Basically your “staging server”

STEPS TO BENCHMARK
Record server load
Run our tests at least 3 times
Take average of tests

BENCHMARKING TOOLS
Apache Bench
Apache Flood
Siege

APACHE BENCH
Shows requests per
second
Bundled with Apache
Gives relative idea of
load

APACHE BENCH - DEMO
1000 Requests with 5 at a time
ab -n 1000 -c 5 http://localhost/phpBB3/index.php
1000 requests with 5 at a time using keep alive
ab -n 1000 -c 5 -k http://localhost/phpBB3/index.php
Output results to Excel / GNUPlot
ab -n 1000 -c 5 -g http://localhost/phpBB3/index.php

ISSUES WITH APACHE BENCH
Synthetic Benchmark
No way to emulate users

APACHE FLOOD
Profile driven
benchmarking
XML Based config
Use variables on pages

XML FORMAT
URLLIST
FARM
FARMER
PROFILE

URLIST
Simple group of URLs
Supports postdelay and predelay

FARMER
Single User
Can use URLLIST in various ways
Random Order
Round Robin
Keep-Alive

FARM
It’s where the farmers work
Controls the way the farmers work
Creates farmers too

PROFILE
Runtime configuration
Can change various settings
socket
report

USE CASES
User visits main page
User visits main page then download page
User visits main page then download and downloads
a file

SINGLE PAGE
Keep Alive
Page Image Image

SINGLE PAGE XML

TWO PAGE VISITS
Keep Alive
Page Image Image
30 secs
later
Keep Alive
Page Image Image

TWO PAGE VISITS XML

TWO PAGE VISITS AND
DOWNOAD
Keep Alive
Page Image Image
30 secs
later
Keep Alive
Page Image Image
15 secs
later
ISO

TWO PAGE VISIT AND
DOWNOAD XML

SETUP A PROFILE
enable keepalive
use the relative times output format
check for 200 OK

PROFILE XML

JOE THE FARMER

FARM FOR JOE TO WORK ON

RUNNING FLOOD
flood <configuration.xml> > output.file
anaylze-relative output.file

VMWARE INSTALL
Run
Run VMware- VMware-
Run VMWare-fusion.dmg
player-2.5.0-118166.exe Player-2.5.0-118166.i386
.bundle
Reboot
Copy Fedora 10 Folder to Disk
Load via VMWare
php / password

TASK
• Visit http://localhost/phpBB3/
• View a forum after 20 seconds
• View a thread after 5 seconds
• Click reply after 60 seconds
• Sample file in flood-examples folder

SIEGE
Provides functionality of Apache Bench and Flood
Supports GET and POST with a simple syntax
Benchmark and Internet mode

SIEGE COMMANDS
1000 Requests with 5 at a time
siege -b -r 1000 -c 5 http://localhost/phpBB3/index.php
10 seconds with concurrency of 5
siege -b -c 5 -t 10 http://localhost/phpBB3/index.php
Read urls.txt for a list of URLs
siege -b -n 1000 -c 5

SPROXY
Creates local socks proxy on your machine
Set your browser to use the local proxy, port 9001
Browse your site with the actions you wish
urls.txt is written with the POST and GET data

OTHER BENCHMARKING
TOOLS
JMeter
httperf
Web Application Stress Tool
OpenWebLoad

PROFILING

WHAT IS PROFILING
Examines the performance characteristics
Records every function call
Tracks execution time
Tracks memory usage

PROFILING TOOLS
XDebug
apd

XDEBUG
Debugger
Code Coverage
Memory and Executon time

XDEBUG PROTECTIONS
Stack overflow in PHP
Infinite Recursion

ERROR MESSAGE HELPING

XDEBUG HELPFUL ERROR
MESSAGES

MORE ERROR MESSAGE
HELPING

EXECUTION TIME

MEMORY USAGE

EXECUTION TRACE
xdebug.auto_trace=1
xdebug.trace_output_dir=/tmp
xdebug.collect_params=1
xdebug.collect_return=1
xdebug.trace_output_name=trace.%c

EXECUTION TRACE

PARTIAL EXECUTION TRACE
Tracing only parts of an application with
xdebug_start_trace() and xdebug_stop_trace().
Fetching the trace file name that is being used with
xdebug_get_tracefile_name().
Changing how much data is shown with
xdebug.var_display_max_children,
xdebug.var_display_max_data and
xdebug.var_display_max_depth.

CODE COVERAGE
Finds unexecuted code
xdebug_start_code_coverage()
xdebug_get_code_coverage()
xdebug_stop_code_coverage()

CODE COVERAGE SAMPLE

CODE COVERAGE OUTPUT

PROFILING
Execute action as normal in browser
Outputs cachegrind file
INI settings:
xdebug.profiler_enable=1 ; enable profiler
xdebug.profile_output_dir=/tmp ; output directory
xdebug.profile_output_name=cachegrind.out.%p

PROFILING CONTINUED
Locate parts of the code that is slow
Work down tree to find the slow sections
Can it be cached? Can it be optimized?
Occasionally built?

VIEWING PROFILE
KCacheGrind
MacCallGrind
WinCacheGrind
Carica CacheGrind

PROFILING DEMO

TASK
sudo nano -w /etc/php.d/xdebug.ini
remove ; from xdebug.profiler_enabled=1
Profile a page on Wordpress
Profile a page on phpBB
Try to find something slow you think could be
improved
20 minutes

APD
Lives in PECL
Similar to XDebug
Doesn’t require KCachegrind
Still only PHP 4

APD
apd_set_pprof_trace() to enable profiler
pprof is a script to interpret the trace
Outputs to apd.dumpdir

BRINGING IT TOGETHER
Use profiler with benchmarks
Profiling can be run on production sites
Optimise slow code

RESOURCES
Lunch - back at 1pm for Caching
http://talks.macvicar.net/
http://httpd.apache.org/test/flood/
http://xdebug.org/docs/
http://www.joedog.org