PHP Performance
w/APC + Memcached
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thaihi5.com

Cache Theory ?

Cache Theory ?
Req
1 Check
2 Miss
Compute
Store 3 Cache
4 Hit
Output
Miss - [Store] - Hit

Type ?
Fast Slow
http://ralphlosey.files.wordpress.com/2007/06/ram.jpg
http://www.pctechguide.com/images/31HardDrive.jpg

APC ?
Alternative PHP Cache

Opcode Cache and Variables Cache
Automatic update w/code changes
Code not changes request

Free & Open Source

Simply Installation

PHP Flow
Req
• Scanning and Lexing
(Plain Text to Tokens)
• Parsing • Scanning
• Lexing
(Tokens to Expressions) • Parsing
• Compilation
• Compilation
(Translated Expressions to Opcode)
• Execution Execution
(Opcode stacks are processed)
Output

Normal PHP vs APC

Normal PHP vs APC
Req
• Scanning
• Lexing
• Parsing
• Compilation
Execution
Output

Normal PHP vs APC
Req
APC hook
• Scanning
• Lexing
• Parsing Miss
• Compilation
APC hook
Store Opcode
cache
Execution
Hit
Output

Installation
• Basic PECL
(http://pecl.php.net)
Conf
– pecl install apc extension=apc.so
apc.shm_segments=1
• Ubuntu apc.shm_size=256
– apt-get install php5-apc apc.optimization=0
apc.num_files_hint=2048
• Windows apc.ttl=3600
apc.user_ttl=3600
(http://pecl4win.php.net) apc.enable_cli=1
apc.max_file_size=1M
– extension=php_apc.dll

Benchmark
PHP Native PHP w/APC
Concurrency Level 10
Time taken for tests 60 seconds
Complete requests 298 914
Total transferred 643,149 bytes 1,962,675 bytes
HTML transferred 516,971 bytes 1,582,035 bytes
Requests per second 4.91 [#/sec] (mean) 15.21 [#/sec] (mean)
Time per request 2035.405 [ms] (mean) 657.623 [ms] (mean)
Time per request 203.541 [ms] 65.762 [ms]
(mean, across all concurrent requests)
Transfer rate 10.35 [KB/s] received 31.88 [KB/s] received

Memcached

History
“Developed by Danga Interactive for
LiveJournal.com”

Memcached ?
• a distributed memory object caching system
with hash table

Memcached ?
• a distributed memory object caching system
with hash table

Memcached ?
• a distributed memory object caching system
with hash table
• a generic two stage hashing system (clients
and servers). Clients are written for specific
application languages. Server is written in C

Memcached ?
• a distributed memory object caching system
with hash table
• a generic two stage hashing system (clients
and servers). Clients are written for specific
application languages. Server is written in C

Memcached ?
• a distributed memory object caching system
with hash table
• a generic two stage hashing system (clients
and servers). Clients are written for specific
application languages. Server is written in C
• 85% of top 20 sites use memcached; 50%+ of
top 5k sites uses Memcached

Memcached ?
• a distributed memory object caching system
with hash table
• a generic two stage hashing system (clients
and servers). Clients are written for specific
application languages. Server is written in C
• 85% of top 20 sites use memcached; 50%+ of
top 5k sites uses Memcached

Why Memcached ?
• Scale-out
– Machine
– Process (Use different ports)
• Memory faster than Disk
• Allows for efficient use of your database
• Can utilize existing network
– Uses non-blocking network I/O (TCP/IP)
• Very flexible
• Client libraries in all major languages

Limits (c/Hash Table)
• Key : max 250 chars.
• Values: max 1MB

“We use more than 800 servers supplying over
28 terabytes of memory to our users.”
“total throughput achieved is 300,000 UDP req/s”
by Paul Saab Saturday, December 13, 2008 at 2:43am
• 8-core machines
• 20-30% CPU usage.
• scale memcached to 8 threads on an 8-core system
• moved to UDP for get operations to reduce network traffic
http://www.facebook.com/note.php?note_id=39391378919

Architecture practical ?
http://barry.files.wordpress.com/2007/04/new-servers-back-04-2007.jpg

Architecture practical ?
“designing & implementing scalable
applications with memcached and mysql”
http://blog.thinkdiff.net/?p=419

Architecture practical ?
http://blog.thinkdiff.net/wp-content/uploads/2009/02/memcache_22-02-2009.png

Coding ? (in PHP)
/* OO API */
$memcacheObj = new Memcache;
$memcacheObj->connect('memcache_host', 11211);
/* set */
$memcacheObj->set('key', 'data', MEMCACHE_COMPRESSED, 50);
/ * get w/single key */
$var = $memcacheObj->get('key');
/ * get w/multiple key */
$var = $memcacheObj->get(array('key1', 'key2'));
$memcacheObj->close();

CMS ?
• Drupal has Memcache API and Integration
http://drupal.org/project/memcache
• Wordpress has object cache
http://mohanjith.net/blog/2008/10/using-memcached-with-
wordpress-object-cache.html

code optimization is best

Discussion
Q&A

Ref.
• Improving PHP Application Performance with APC
http://www.slideshare.net/vortexau/improving-php-application-
performance-with-apc-presentation
• PHP Accelerators : APC vs Zend vs XCache with Zend
Framework
http://blog.digitalstruct.com/2007/12/23/php-accelerators-apc-vs-zend-vs-
xcache-with-zend-framework/
• Scaling with memcached
http://www.slideshare.net/acme/scaling-with-memcached
• Gear6 and Scaling Website Performance: Caching Session and
Profile Data with Memcached
http://www.slideshare.net/gear6memcached/gear6-and-scaling-website-
performance-caching-session-and-profile-data-with-memcached

Ref. (2)
• PHP: Memcache - Manual
http://th.php.net/manual/en/book.memcache.php
• http://danga.com/memcached/
• http://pecl.php.net/package/memcache
• http://www.socialtext.net/memcached/

Thank you
@FordAntiTrust
http://www.slideshare.net/FordAntiTrust