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  • 1. OPTIMIZING SOA WITH PHP By Glen Campbell, Engineering Manager Yahoo! Tech http://tech.yahoo.com 1
  • 2. About Yahoo! Tech • Launched May 1, 2006 • First new site launched by the Yahoo! Media group in over five years • First Yahoo! site to use a complete service- oriented architecture • First Yahoo! site to use MAPLE (the Media Presentation Layer) written in PHP • #1/#2 site in the Technology/Gadgets niche 02-Oct-07 OPTIMIZING SOA WITH PHP 2 2
  • 3. INTRODUCTION Let’s make sure we’re saying the same thing... 3
  • 4. Some Definitions • SOA—Service-Oriented Architecture. A structure for delivering content via services (as opposed to via databases or static content). • REST—Representational State Transfer. An “architectural style” for implementing services using an existing HTTP infrastructure. 02-Oct-07 OPTIMIZING SOA WITH PHP 4 4
  • 5. What is REST? • Resources are represented by URLs • Actions use HTTP methods (GET, POST, PUT, DELETE) • Some resources: § Representational State Transfer http://www.ics.uci.edu/~fielding/pubs/dissertation/ rest_arch_style.htm § How I Explained REST to my Wife http://tomayko.com/articles/2004/12/12/rest-to- my-wife 02-Oct-07 OPTIMIZING SOA WITH PHP 5 5
  • 6. The Data Transfer Stack • Time to read 1K of data: § CPU cache = 80ns § PC-3200 DDR RAM = 350ns § SATA hard disk = 17μs § 1000Mbit network = 20μs (plus latency) § 100Mbit network = 160μs • Faster is better • Closer is faster 02-Oct-07 OPTIMIZING SOA WITH PHP 6 6
  • 7. Implications of SOA • Content is stored on the network • Content is non-local, and therefore slow • Content is highly redundant, and therefore cacheable • Performance is contingent upon several things: § Network optimization § Parallelism § Caching 02-Oct-07 OPTIMIZING SOA WITH PHP 7 7
  • 8. What, exactly, are you talking about? A real-world example from Yahoo! Tech 8
  • 9. Yahoo! Tech traffic patterns Where do the spikes come from? 02-Oct-07 OPTIMIZING SOA WITH PHP 9 9
  • 10. The Yahoo! Front Page • The most-visited page on the Internet • Featured position F1 drives a huge amount of traffic 02-Oct-07 OPTIMIZING SOA WITH PHP 10 10
  • 11. Current Architecture Maple (PHP5) FE Other Services SQUID API MySQL PHP4 (PHP5) 02-Oct-07 OPTIMIZING SOA WITH PHP 11 11
  • 12. Lessons Learned Tips and Tricks 12
  • 13. Parallelism • For services, the latency is in the network; using parallel requests can save time • The multi-curl extension to PHP: // create both cURL resources $ch1 = curl_init(); $ch2 = curl_init(); // set URL and other appropriate options curl_setopt($ch1, CURLOPT_URL, "http://www.example.com/"); curl_setopt($ch1, CURLOPT_HEADER, 0); curl_setopt($ch2, CURLOPT_URL, "http://www.php.net/"); curl_setopt($ch2, CURLOPT_HEADER, 0); //create the multiple cURL handle $mh = curl_multi_init(); //add the two handles curl_multi_add_handle($mh,$ch1); curl_multi_add_handle($mh,$ch2); $running=null; //execute the handles do {     curl_multi_exec($mh,$running); } while ($running > 0); //close the handles curl_multi_remove_handle($ch1); curl_multi_remove_handle($ch2); 02-Oct-07 OPTIMIZING SOA WITH PHP 13 13
  • 14. Parallelism • Preceding example is not optimal; still waits until all services are fetched before proceeding • Maple begins rendering a component as soon as the service finishes executing 02-Oct-07 OPTIMIZING SOA WITH PHP 14 14
  • 15. HTTP Cache • REST services are cacheable • Using HTTP allows any HTTP-compatible caching intermediary or proxy (e.g., squid) • Services should use Expires: or Cache-Control: headers: Cache-Control: max-age=600 • HTTP controls caching (GET, POST, PUT, DELETE) 02-Oct-07 OPTIMIZING SOA WITH PHP 15 15
  • 16. How to use a caching proxy in PHP (curl) // retries a single URL via CURL function fetch_curl($url, $timeout=5) { $ch = curl_init($url); curl_setopt($ch, CURLOPT_HEADER, 0); curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); curl_setopt($ch, CURLOPT_TIMEOUT, $timeout); curl_setopt($ch, CURLOPT_PROXY, ‘127.0.0.1:3128’); $payload = curl_exec($ch); return $payload; } 02-Oct-07 OPTIMIZING SOA WITH PHP 16 16
  • 17. How much effect does caching have? • Yahoo! Tech, without caching: 0.6 requests/second per server • With squid cache: 15.5 requests/second per server • 2,400% increase! • Or, in hardware terms, 16 servers instead of 400 02-Oct-07 OPTIMIZING SOA WITH PHP 17 17
  • 18. Squid • Open-source, industry-standard HTTP proxy • Highly configurable • Single-threaded (sigh) • Handles ~7,000 requests/second on average hardware 02-Oct-07 OPTIMIZING SOA WITH PHP 18 18
  • 19. How to make Squid faster • Give it more RAM • Use heap LFUDA cache replacement policy (keeps frequently-accessed objects in cache longer) • Give it more RAM • Use refresh_stale_hit • Give it more RAM • Use collapsed_forwarding • Did I mention to give it more RAM? 02-Oct-07 OPTIMIZING SOA WITH PHP 19 19
  • 20. Other things you can do with Squid • Clustering (cache_peer) effectively doubles the throughput of the cache (think multi-threaded) • Always use timeouts, if possible (never wait for anything) 02-Oct-07 OPTIMIZING SOA WITH PHP 20 20
  • 21. Network Interface Optimization • Um, gigabit anyone? • Seriously, use as fast a NIC as you can afford. 02-Oct-07 OPTIMIZING SOA WITH PHP 21 21
  • 22. PHP-specific • Use absolute paths require ‘/usr/local/lib/php/something.inc’; instead of relative require ‘something.inc’; • Significant performance improvements 02-Oct-07 OPTIMIZING SOA WITH PHP 22 22
  • 23. PHP-specific, 2 • CURL sends Pragma: no-cache by default, ensuring that your content is never cached • To avoid this: curl_setopt($ch, CURLOPT_HTTPHEADER, array(‘Pragma:’)); 02-Oct-07 OPTIMIZING SOA WITH PHP 23 23
  • 24. PHP-specific, 3 • Avoid open_basedir • Ok, it’s a security risk, but it’s also a performance hit • Weigh the options and decide 02-Oct-07 OPTIMIZING SOA WITH PHP 24 24
  • 25. XML performance optimization • Never parse an XML document twice • Pass a DOM handle or SimpleXML object around 02-Oct-07 OPTIMIZING SOA WITH PHP 25 25
  • 26. Plan for failure • Always specify a timeout • Always have behavior planned in case of a timeout • Tune your timeouts for optimal effect 02-Oct-07 OPTIMIZING SOA WITH PHP 26 26
  • 27. Questions and Answers Speak up! I can’t hear you in the back! 27
  • 28. More information • Download these slides: http://files.broadpool.com/zendcon2007/ • Email me: glen.campbell@mac.com • Listen to me again: Washington, DC, PHP Conference, Nov 9th • Read my blogs: http://broadpool.com http://dailyfunnies.org http://suburbanredneck.org http://techbreakfast.org 02-Oct-07 OPTIMIZING SOA WITH PHP 28 28