Parallel Processing in PHP Fork It ! Nathaniel McHugh Monday, 8 October 12 

• Software Engineer Inviqa • @natmchugh • http://fishtrap.co.uk • likes doing useless PHP Monday, 8 October 12 

Monday, 8 October 12 

Pasta or Monday, 8 October 12 

0 1 2 3 4 5 6 7 8 9 10 1 cup 2 cups 3 cups 4 cups t (minutes) kettle hob microwave Monday, 8 October 12 

Monday, 8 October 12 

Number of Processors https://github.com/natmchugh/PHP-Num- Processors php > echo num_processors_available(); 2 php > echo num_processors_configured(); 2 Monday, 8 October 12 

Forking • php has no multi threading • pcntl extension • *nix only • cli only really Monday, 8 October 12 

fork() Monday, 8 October 12 

fork() $ ps -a | grep ps 3394 ttys003 0:00.00 ps -a 3395 ttys003 0:00.00 grep ps $ Monday, 8 October 12 

fork() $ ps -a | grep ps 3394 ttys003 0:00.00 ps -a 3395 ttys003 0:00.00 grep ps $ $ man fork | grep returns Upon successful completion, fork() returns a value of 0 to the child process and returns the process ID of the child process to the parent Monday, 8 October 12 

Monday, 8 October 12 

Concurrency real 1m10.322s real 0m39.928s real 0m45.827s Monday, 8 October 12 

Die Hard PHP Daemons doSomeWork(); } Monday, 8 October 12 

From the Beginning Monday, 8 October 12 

From the Beginning $ php start_with_manual.php $ Monday, 8 October 12 

• Zombies are dead • Orphans are children whose parent has died Zombies vs Orphans Monday, 8 October 12 

multiple children?

multiple children?

multiple children?

multiple children?

The Pattern require('deep_thought.php'); $deepThought = new DeepThought(); $children = array(); for ($i=0; $i < 5; $i++) { $children[] = $pid = pcntl_fork(); if ($pid == -1) { die('could not fork'); } else if (0 === $pid) { $lifeUniverseEverthing = $deepThought->findTheAnswer(); echo "Child $i says:",$lifeUniverseEverthing,PHP_EOL; die(); } } do { $pid = pcntl_wait($status); $children = array_diff($children, array($pid)); } while (count($children) > 0); Monday, 8 October 12 

The Pattern require('deep_thought.php'); $deepThought = new DeepThought(); $children = array(); for ($i=0; $i < 5; $i++) { $children[] = $pid = pcntl_fork(); if ($pid == -1) { die('could not fork'); } else if (0 === $pid) { $lifeUniverseEverthing = $deepThought->findTheAnswer(); echo "Child $i says:",$lifeUniverseEverthing,PHP_EOL; die(); } } do { $pid = pcntl_wait($status); $children = array_diff($children, array($pid)); } while (count($children) > 0); $ time php the_pattern.php Child 0 says:42 Child 3 says:42 Child 1 says:Child 2 says:42 42 Child 4 says:42 real 0m5.453s user 0m0.056s sys 0m0.060s $ Monday, 8 October 12 

Signals

Signals

SIGCHLD 0) { $children = array_diff($children, array($pid)); echo "Child $pid collected".PHP_EOL; } } Monday, 8 October 12 

SIGCHLD 0) { $children = array_diff($children, array($pid)); echo "Child $pid collected".PHP_EOL; } } php sigchld.php ....Child 0 says:42 Child 2 says:42 Child 3 says:42 Child 1 says:42 Child 4 says:42 .Caught SIGCHLD Child 22877 collected Child 22876 collected Child 22874 collected .Caught SIGCHLD Child 22875 collected .Caught SIGCHLD Child 22878 collected Monday, 8 October 12 

Process Isolation

Process Isolation

Resources

Resources $ php resources.php Parent Child $ php resources.php Child Parent $

How do you get your children to talk to you? Monday, 8 October 12 

Listening to your children • DB • files • memcached, apc or shared memory • sockets Monday, 8 October 12 

Sockets Example findTheAnswer(); writeToSocket($data, $sockets[0]); die(); } } do { $pid = pcntl_wait($status); $forks = array_diff($forks, array($pid)); $sockets = $socketPairs[$pid]; $data = readFromSocket($sockets[1]); var_dump($data); } while (count($forks) > 0); Monday, 8 October 12 

Next Level • Gearman • Message Queues ØMQ, RabbitMQ .. Monday, 8 October 12 

Thinking Parallel “It turns out that what was difficult, and almost impossible, is to take an ordinary program and automatically figure out how to use the parallel computation effectively...” Richard P. Feynman Monday, 8 October 12 

Input Processing Output Input Input Input Processing Processing Output Output Output Monday, 8 October 12 

• Even Distribution of work /input • Size of messages • Data Dependancies Monday, 8 October 12 

PHPLOC input: file system output: array of stats processing: tokenize and count occurrences Monday, 8 October 12 

PHPLOC array(1781) { [0] => string(51) "zf2/bin/autoload_example.php" [1] => string(52) "zf2/bin/ autoload_examples.php" [2] => string(53) "zf2/bin/ classmap_generator.php" [3] => string(60) "zf2/bin/ createAutoloadTestClasses.php" [4] => string(54) "zf2/bin/ pluginmap_generator.php" ... foreach ($files as $key => $file) { $directory = dirname($file); if (!isset($this->directories[$directory])) { $this->directories[$directory] = TRUE; } ... Monday, 8 October 12 

PHPLOC real 0m7.216s user 0m6.492s sys 0m0.240s $ time phploc --cores 1 zf2 $ time phploc --cores 2 zf2 real 0m5.500s user 0m6.686s sys 0m0.293s https://github.com/natmchugh/phploc Monday, 8 October 12 

Amdahls Law Monday, 8 October 12 

Embarrassingly Parallel Monday, 8 October 12 

Mandelbrot Set Input: Pixel co-ordinates Processing: Hard core number crunching Output: An image Monday, 8 October 12 

Dividing Work https://github.com/natmchugh/PHP-Fractals Monday, 8 October 12 

Thanks Joind.in: http://joind.in/7002 @natmchugh http://fishtrap.co.uk Monday, 8 October 12 

• Front Fork http://www.flickr.com/photos/de_atienza/ • Paint, Laptop & fork Lift http://consumeconsume.com/ • Haynes Manual http://www.flickr.com/photos/8490341@N04/ • Zombie Child http://www.flickr.com/photos/zenobia_joy/ • Signal http://www.flickr.com/photos/rbrwr/ • Pattern http://www.flickr.com/photos/eadaoinflynn Monday, 8 October 12