Effectice Caching w/ PHP + Caching

EFFECTIVE CACHING WITH PHP & MEMCACHED by Justin Carmony

ABOUT ME • Full Time Web Developer & Consultant • Worked with LAMP & .NET Solutions • Blog - http://www.justincarmony.com/blog/ • Current Projects:

ABOUT PRESENTATION On-Topic Questions During Presentation Q & A Session After Presentation Feel Free to Email Me Questions: justin@justincarmony.com

WHAT IS MEMCACHED?

ABOUT MEMCACHED

ABOUT MEMCACHED Developed by LiveJournal’s Developers

ABOUT MEMCACHED Developed by LiveJournal’s Developers Primary Function: Relieve Database Load (Mainly Reads)

ABOUT MEMCACHED Developed by LiveJournal’s Developers Primary Function: Relieve Database Load (Mainly Reads) Can Scale Across Multiple Servers

ABOUT MEMCACHED Developed by LiveJournal’s Developers Primary Function: Relieve Database Load (Mainly Reads) Can Scale Across Multiple Servers Giant “Hash Table” or “Array”

ABOUT MEMCACHED Developed by LiveJournal’s Developers Primary Function: Relieve Database Load (Mainly Reads) Can Scale Across Multiple Servers Giant “Hash Table” or “Array” Stores Data in Memory - Extremely Fast

WHY WE CACHE

CONCEPT OF CACHING

CONCEPT OF CACHING • Resource that is Struggling Website Resource Application

CONCEPT OF CACHING • Resource that is Struggling Website • Introduce Cache to Help Resource Application Cache

CONCEPT OF CACHING • Resource that is Struggling Website • Introduce Cache to Help Resource Application • Store “Reliable” Data in Cache Cache

CONCEPT OF CACHING • Resource that is Struggling Website • Introduce Cache to Help Resource Application • Store “Reliable” Data in Cache • Check Cache Before Hitting Resource Cache

CONCEPT OF CACHING • Resource that is Struggling Website • Introduce Cache to Help Resource Application • Store “Reliable” Data in Cache • Check Cache Before Hitting Resource Cache • Resource Types: DB, Web Service, XML, Files, Etc.

THE DATABASE

THE DATABASE • Scaling is Complicated

THE DATABASE • Scaling is Complicated • Its because what makes databases great: ACID.

THE DATABASE • Scaling is Complicated • Its because what makes databases great: ACID. • What about SQL’s Internal Caching?

THE DATABASE • Scaling is Complicated • Its because what makes databases great: ACID. • What about SQL’s Internal Caching? • Less Load on DB is Good

HOW DOES IT IMPROVE PERFORMANCE?

DATING DNA PERFORMANCE BOOST Before After Daily New Registrations 100 500 HTTP Requests Per Second ~ 36 r/s ~150 r/s AVG Database CPU ~ 73% ~32% # Queries Per Second ~ 2,200 ~1,700 AVG Page Load Time 2 - 5 seconds 0.01 - 0.4 seconds * Note - Several Performance Changes Made, Not 100% Due to Memcached

LIVE MEMCACHED STATS

INSTALLING & RUNNING MEMCACHED

INSTALLING • Linux - Aptitude, Yum, RPM, Compile from Source, etc... • Mac OS X - Compile Only • Windows - Downloadable Binaries • Its pretty simple!

RUNNING • No Conﬁguration Files • Just a few command line options: memcached -d -m 2048 -l 127.0.0.1 -p 11211

BASIC CACHE FLOW

CONNECT <?php // Create New Memcache Instance $memcache = new Memcache(); // Add Memcache Server to Connection Pool $memcache->addServer('127.0.0.1', 11211); // ... continue code ...

GET & SET DATA // Try to Get the $my_name = $memcache->get('my_name'); if($my_name === false) { $my_name = 'Justin Carmony'; $memcache->set('my_name', $my_name, false, 60); } echo $my_name; // output: Justin Carmony

“DELETING” DATA // Lets say we don't like Justin anymore... $memcache->delete('my_name'); $value = $memcache->get('my_name'); // returns false

CACHING THEORY ( WHERE, WHAT, WHEN, & HOW)

WHERE TO CACHE

IDENTIFYING WHAT TO CACHE

IDENTIFYING WHAT TO CACHE ‣ High Demand

IDENTIFYING WHAT TO CACHE ‣ High Demand ‣ Expensive

IDENTIFYING WHAT TO CACHE ‣ High Demand ‣ Expensive ‣ Large in Size

IDENTIFYING WHAT TO CACHE ‣ High Demand ‣ Expensive ‣ Large in Size ‣ Common

IDENTIFYING WHAT TO CACHE ‣ High Demand ‣ Expensive ‣ Large in Size ‣ Common The Best Cacheable Data with Highest Performance ROI Fits Multiple Characteristics

TIPS FOR FINDING CACHEABLE DATA

TIPS FOR FINDING CACHEABLE DATA ‣ Monitor Queries

TIPS FOR FINDING CACHEABLE DATA ‣ Monitor Queries ‣ Output Queries

TIPS FOR FINDING CACHEABLE DATA ‣ Monitor Queries ‣ Output Queries ‣ Monitor Page Loads

TIPS FOR FINDING CACHEABLE DATA ‣ Monitor Queries ‣ Output Queries ‣ Monitor Page Loads ‣ Monitor Web Analytics

TIPS FOR FINDING CACHEABLE DATA ‣ Monitor Queries ‣ Output Queries ‣ Monitor Page Loads ‣ Monitor Web Analytics ‣ Brainstorming

WHAT TO CACHE

OUTPUT CACHING Capture Output Buffer When to Use Output Caching: - Page Has High Load - Expensive to Generate - Easier to Cache over Data

OUTPUT BUFFER EXAMPLE // Output Buffer Cache $output = $memcache->get('my_html'); if(!$output) { ob_start(); // Start Capture ?> <div id="main">Hello World!</div>  <?php $output = ob_get_contents(); ob_end_clean(); $memcache->set('my_html', $output, false, 15 * 60); } echo $output;

DATA CACHING Create a Class to Cache Use Factory Methods to Retrieve Use When Use: - Data Used Frequently - Displayed Different - Easier from Cache than other Sources

WHEN TO EXPIRE

TIMEOUT EXPIRATION Settings a Lower Timeout Great for Summaries Okay to be Kinda Out of Date “Quick & Dirty” Optimizations Output + Timeout Common

EVENT EXPIRATION Data is Infrequently Updated Data is Time Critical - Cannot Be Out of Date Data + Event Common

HOW TO CACHE

IT’S ALL ABOUT YOUR KEYS Keys MUST Be Unique Prefix Cache Types (i.e. prflinfo_ for ProfileInfo) SHA256 / MD5 Identifiers Example: ProfileInfo for User ID 1337: prflinfo_e48e13207341b6bffb7fb1622282247b

WRAP YOUR CACHE W/ CLASS Pick a Cacheable Piece of Information Create a Class For That Cache Create Methods For: ‣ Generate Key Name ‣ Get & Set ‣ Destroy / Delete

class ProfileInformation { public $user_id = null; public $first_name = null; public $email_address = null; public $profile_img = null; public $city = null; public $state = null; public $age = null; private function __construct($user_id) { $this->user_id = $user_id; $sql = "SELECT * FROM users WHERE user_id = '$user_id'"; $p_data = DBI::fetchObject($sql); $this->first_name = $p_data->first_name; $this->email_address = $p_data->email_address; $this->age = xDate::GetAge($p_data->birthdate); // .. Set More Information .. } // .. more .. }

class ProfileInformation { // .. more .. static public function GetProfile($user_id) { // Try to get it from the cache $profile = null; $profile = self::GetCache($user_id); if(!$profile) { $profile = new ProfileInformation($user_id); self::SetCache($user_id, $profile); } return $profile; } // ... more ... }

class ProfileInformation { // .. more .. static protected function GetCacheName($user_id) { return 'profile_'.hash('sha256',"user_".$user_id."_".$user_id); } // ... more ... }

class ProfileInformation { // .. more .. static protected function GetCache($user_id) { $name = self::GetCacheName($user_id); $profile = null; $memcache = MemcacheCluster::GetInstance(); $profile = $memcache->get($name); if(!$profile) { return null; } return $profile; } // ... more ... }

class ProfileInformation { // .. more .. static protected function SetCache($user_id, $data) { $name = self::GetCacheName($user_id); $memcache = MemcacheCluster::GetInstance(); $profile = $memcache->set($name, $data, false, 24 * 60 * 60); } public static function DestroyCache($user_id) { $name = self::GetCacheName($user_id); $memcache = MemcacheCluster::GetInstance(); $profile = $memcache->delete($name); } // End Of Class }

require_once 'ProfileInformation.class.php'; $user_id = 1337; // Incorrect Method $profile = new ProfileInformation($user_id); // Throws Error // Correct Method $profile = ProfileInformation::GetProfile($user_id); echo $profile->first_name;

FINAL THOUGHTS

COMMON PITFALLS • Caching Only Optimization - Ignoring Other Inefficiencies • Cache Offline == Catastrophic Failure • Poor Key Choices • Inability to easily invalidate specific Cache Entries • Caching SQL Queries

PITFALL: QUERY CACHE <?php $sql = "SELECT * FROM users WHERE id = 5"; $result = $mem->get(md5($sql)); if(!$result) { // Execute and get the result of the query in an array $result = Database::FetchArray($sql); // set the timeout to 4 hours $mem->set(md5($sql), $result, 0, 4 * 60 * 60); } ?>

SECURITY No Real Security for Memcached --listen Not Super Secure / Conﬁgurable Limit Access at Network Level IPTables / Firewalls / Internal Network

MISCELLANEOUS THINGS Memcache Library vs Memcached Library Where can I ﬁnd out More? - My Blog: Search Memcached - Google Memcached - PHP Documentation

QUESTIONS?

SHAMELESS PLUG: October 8-10, 2009 | www.utosc.com

THANK YOU Website www.justincarmony.com Email justin@justincarmony.com Twitter JustinCarmony Skype JustinCarmony IRC irc.freenode.net #uphpu

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Effectice Caching w/ PHP + Caching

by Justin Carmony

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Effectice Caching w/ PHP + Caching Presentation Transcript