Bumping our Stack to PHP 5.5

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Glen Mailer

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A short  audience survey

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Set the Scene  (as of September 2013)

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The Codebase

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First commit April 2010  60k commits since According to git

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9300 PHP files  690k lines of code According to cloc

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10 releases a week  35 active committers  10 concurrent streams  1 deployable

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The Platform

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8 Test Environments  1 Staging Environment  2 Live Environments

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74 Live PHP boxes

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1300 req/s peak  500k uniques/week

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Why Upgrade?

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Using basically the same PHP version as the first commit with security patches

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PHP 5.3 is dead

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Bug fixes  Performance

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New Features! short array syntax traits $this in closures yield finally

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Bug #64827  GC causes segfaults

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The Plan

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Upgrade a dev box Support 5.3 and 5.5 Pass all tests Upgrade 1 Test env Upgrade CI Upgrade Test & Staging Incrementally Upgrade Live

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Vagrant  Chef  Unit Tests  Acceptance Tests

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Hack hack hack...

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3 days later

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What changed?

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APC  becomes  OPcache and APCu

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Check for new function, fall back to old one if (function_exists('opcache_reset')) { opcache_reset(); } else { apc_clear_cache(); }

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“The PHP api will retain compatibility with APC, as will common configuration options, providing a drop in replacement.” APCu

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Not a drop in replacement

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APCu 4.0.1  APCu 4.0.2  master is closer still

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No more  mysql_

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It will not be missed

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preg_replace /e  becomes  preg_replace_callback

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(string) array()  Now raises a warning Still returns “Array”

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"Type-checked" function function inc($int) { if (!is_int($int)) { throw new InvalidArgumentException( 'Expected int, got: ' . $int ); } return $int + 1; }

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Unit test for type-checked function /** * @dataprovider provideIncInvalid */ function testIncRejectsInvalid($a) { try { inc($a); $this->fail('Expected exception'); } catch (InvalidArgumentException $ex) {} } function provideIncInvalid() { return array( null, true, "string", array() ); }

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Simplest fix throw new InvalidArgumentException( 'Expected int, got: ' . json_encode($int) );

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$a = "string”;  $a['index'];  Now raises a warning

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// protected $a;  ++$this->a  Now raises a warning

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Progress

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Upgrade a dev box  Support 5.3 and 5.5  Pass all tests  Upgrade 1 Test env  Upgrade CI  Upgrade Test & Staging  Incrementally Upgrade Live

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Upgrade a dev box  Support 5.3 and 5.5  Pass all tests  Upgrade 1 Test env  Upgrade CI  Upgrade Test & Staging  Incrementally Upgrade Live

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PHPNW 2013

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The Rollout

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APCu Failures  APCu #49: Segfaults  APCu #19: deadlock

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Forwards  or  Backwards

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Segfaults - 100 point Moving Average 7.2/s 6.0/s 4.8/s 3.6/s 2.4/s 1.2/s Oct Nov Dec Jan

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Shared Memory?  I'm out.

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Can we  leverage OPCache?

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The Barwell Cache

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function barwell_store($key, $value) { $path = BARWELL_BASE . '/' . md5($key); file_put_contents( $path, '

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function barwell_store_obj($key, $value) { $path = BARWELL_BASE . '/' . md5($key); file_put_contents( $path, '

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Are you mad?

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Probably.

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Take a moment.  Stop.  Think.

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What is the problem we're trying to solve?

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Fast k/v access  for hot paths

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How fast do we really need to be?

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Move almost everything over to memcached

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Autoload Map  Environment Config  Weird Zend Reflection

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function simple_store($key, $value) { file_put_contents( path($key), serialize($value)); } function simple_fetch($key) { return unserialize( file_get_contents(path($key))); }

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The  Aftermath

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Performance

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Average Response Time in ms

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Average Memory Use in MB

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Average Response Time in ms  on one API endpoint with minimal external calling