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SitePoint PHP Blog:
Caching Hat-trick: Zend Opcache, Etags and Query Caching
Jul 13, 2015 @ 09:57:56

The SitePoint PHP blog has posted three tips on caching that can help speed up your application from the processing level up. The article shares tips on using opcode caching for faster processing, etags for web request caching and query caching on the data side.

In this article, we will be looking at some of the common caching techniques in PHP: Opcache, Expires Headers and Query Caching in MySQL. We’ll look at additional approaches in part 2.

He starts with an introduction to the request lifecycle of a typical request made to a PHP-based application, from the fetching of a file to the actual execution. This lays the groundwork for the first kind of caching: opcodes for caching execution results. He helps you get that enabled and configured and shows how to determine how much it's actually helping. Following this he talks about the "expires" headers you can send from Apache, telling the browser exactly when it needs to fetch new versions of things like CSS, image or Javascript files. Finally he touches on MySQL query caching, storing the already parsed version of a query on the server with results in a cache for faster polling on repeated requests.

tagged: caching zend opcode etags expires query caching tutorial speed performance

Link: http://www.sitepoint.com/caching-hat-trick-zend-opcache-etags-and-query-caching/

Tideways.io:
Essential Macro Optimizations to Improve PHP Performance
Jul 09, 2015 @ 10:19:16

The Tideways.io blog has posted a set of four macro-optimizations you can do to help improve the overall performance of your application. Note the "macro" here, not "micro", so these are larger, more platform-level changes.

This blog post describes four macro-optimizations for PHP applications that are essential to consider before investigating other possible optimizations. [...] While its fun chasing after small micro optimizations, often it is debatable if the developer time is well spent. After all I/O is the more important bottleneck in almost every application. [...] But its much more efficient to fix the big issues first. The changes I present in this post can be done quickly and their gains can be massive.

The four suggestions he makes cover different areas of a standard application:

  • Upgrade PHP to a recent version
  • Use accelerator such as APC or OPCache
  • Close Session for Writes
  • Don't run XDebug in Production

Each tip comes with a bit of background on why it's a good idea and some have links to other resources supporting the change or update proposed.

tagged: macrooptimization performance application version opcode cache session write xdebug

Link: https://tideways.io/profiler/blog/essential-macro-optimizations-to-improve-php-performance

Julien Pauli:
On PHP function calls
Jan 22, 2015 @ 09:58:39

Julien Pauli has a new post today sharing an interesting function optimization he found using the Blackfire execution profiler.

This blog post is a technical explanation of a PHP optimization found with BlackFire profiler into a PHP script. The related post is located here : http://blog.blackfire.io/owncloud.html

He found that a replacement of a call to strlen with an isset optimized the script by about 20%. It's not typical though, he explains. He points out that the optimization worked so well because the call was part of a loop. He gets into some of the "under the covers" details of why this speed boost happens and even includes the op code output showing the difference. He then starts getting deep into the internal code for PHP and walks through each step made in the evaluation of a string's length. He finishes the post looking at isset (not technically a function) and how it handles its data checking. He also includes information about opcode caching and how to best maximize its impact.

tagged: function call strlen loop isset internals opcode cache performance

Link: http://jpauli.github.io/2015/01/22/on-php-function-calls.html

Derick Rethans:
Code Coverage: The Present
Dec 02, 2014 @ 11:54:01

Derick Rethans has posted the first in a series focusing on the Xdebug tool and the code coverage functionality it can provide via PHPUnit's testing. In this first post he catches the reader up on the current state of things and what all the Xdebug tool can do.

Since ages Xdebug has provided code coverage support for PHPUnit, a way to show which lines are covered by your test cases. But I never really wrote about how it works. A recently filed bug prompted me to write this post, as well as a follow up post on Code Coverage's future.

He starts off with the early days of Xdebug, how it hooked into the Zend Engine (that powers a lot of PHP behind the scenes) and when it was triggered. This came with its own set of problems so Xdebug was updated to overload some opcodes. He talks about how it can calculate the unused lines and determines which lines can be covered in the code coverage results. He provides some example code showing the execution of the coverage report on a simple function and try/catch handler, complete with the HTML output of the results.

tagged: xdebug codecoverage phpunit coverage history functionality opcode

Link: http://derickrethans.nl/code-coverage.html

SitePoint PHP Blog:
Understanding OpCache
Jul 30, 2014 @ 10:39:27

On the SitePoint PHP blog there's a new tutorial posted helping you understand OpCache, the caching engine built into PHP versions 5.5 and above. This cache isn't designed to cache data or other content, though. An OpCache caches "opcodes" when a script is executed.

PHP in version 5.5 comes with a caching engine built-in – OpCache – which stores precompiled script bytecode in the memory. If you’re familiar with APC or Xcache, you will already know how such engines work. As each PHP script is being compiled at runtime, a part of the execution time gets used for transforming the human readable code into code that can be understood by the machine. A bytecode cache engine like OpCache, APC or Xcache does it only once – during the first execution of a specific PHP file. Then the precompiled script is being stored in memory, which should lead to performance boosts in your PHP applications.

The remainder of the article is a series of answers to some common questions about using the cache, what it will do for your applications and some tools to use for tuning and status updates:

  • Is OpCache worth installing at all? What speed boost can I expect?
  • I already use APC cache. Should I migrate to OpCache?
  • How to check if OpCache is actually caching my files?
  • Is there any framework-specific config that I should set?
  • I keep my app config in a PHP file. Can I prevent it from being cached?
  • How can I run both a development and a production environment on a single server where OpCache is enabled?
tagged: opcache opcode cache tutorial introduction php55 bytecode

Link: http://www.sitepoint.com/understanding-opcache/

Davey Shafik:
Everything You Need to Know About OpCode Caches
Oct 01, 2013 @ 10:49:48

Davey Shafik has a new post to his site today sharing everything you need to know about opcode caches, the mechanism that's works "behind the scenes" to cache the execution of the opcode paths for later reuse.

Last year I wrote a talk called “Fast, Not Furious: How to Find and Fix Slow Code” - a performance talk covering profiling, memcache and some other stuff. As I often do - to hedge my bets = I stuck a few slides on the end “just in case” I ran through everything too quickly and needed to fill in time. These slides were on APC, the Alternative PHP Cache, and went just a little into tokens and how APC works under the hood. I really enjoyed presenting those 6 slides, and I’ve been wanting to expand on that topic ever since then. Well, after a few weeks of hard work, some input from some great people, including Sara Golemon, Elizabeth Smith and Julien Pauli, I’m so very happy to publish PHP Performance I: Everything You Need to Know About OpCode Caches.

The result is published over on the Engine Yard Developer Center and has been made into a 20 minute screencast (with original slides here). He covers what they are, which ones are out there, the common execution cycle and what happens when the opcodes are cached.

tagged: opcode cache presentation screencast guide tutorial apc zend opcache

Link: http://daveyshafik.com/archives/68838-everything-you-need-to-know-about-opcode-caches.html

Nikita Popov:
Order of evaluation in PHP
Sep 25, 2013 @ 10:51:35

If you're the kind of person that wonders more about the internals of PHP and how it works "under the covers" you'll find this new post from Nikita Popov a good read. It talks about how PHP handles its order of operations in more complex evaluation statements.

At this point many people seem to think that the order in which an expression is evaluated is determined by operator precedence and associativity. But that's not true. Precedence and associativity only tell you how the expressions are grouped.[...] What does this tell us about the order of evaluation? Nothing. Operator precedence and associativity specify grouping, but they do not specify in which order the groups are executed.

He gives a few examples to illustrate his point including multiple increments of the same variable at one time and how it's the "fault" of the compiled variables that were introduced in PHP 5.1. He shows the opcode version of the same PHP userland code and talks briefly about how to avoid this odd functionality in your application.

tagged: order evaluation opcode compiled variable

Link: https://gist.github.com/nikic/6699370

Chris Jones:
Using PHP 5.5's New "Opcache" Opcode Cache
Mar 18, 2013 @ 09:42:55

Chris Jones has a new post to his Oracle blog today talking about the new "opcode" opcode caching that's going to be built into future PHP versions This is the implementation of the Zend Optimizer+ opcode caching in a native language interface. The latest PHP 5.5 snapshots have it included.

The new "opcache" can be seen as substitute for the venerable APC cache, the maintenance of which had become an issue. Note: although opcache is now readily available, there is currently nothing preventing you from using any available (working!) opcode cache in PHP 5.5.

He gives you a quick guide to getting this new opcode caching enabled and compiled into a shiny new download of the PHP 5.5.x branch. You'll need a special command line flag on the compile and to update your php.ini to load the needed shares module. You can also use it if you're on PHP 5.2 or higher either by compiling this source or using this PECL extension.

tagged: opcode cache zendoptimizer install configure phpini pecl

Link:

Lukas Smith:
On predictable PHP release cycles
Mar 01, 2013 @ 09:37:52

Lukas Smith has a new post today about what he sees as an important part of PHP (or really most open source projects) - a predictable release cycle. It centers around the recent proposal to introduce the Zend Optimizer+ into the core and how it seems to be causing a delay with 5.5 (maybe up to 2 months).

What troubles me though is that its being proposed very late in the game for PHP 5.5, therefore causing a likely delay of 5.5 of at least about 2 months in the best case scenario if it were included. The other option of including it in 5.6 does not seem to be as popular at this point. This saddens me quite a bit since I believe that predictable release cycles would carry several advantages

He points out some things that come along with having predicability around the software releases like developers knowing when/if their changes will make it into the next release. It also makes it easier for end users to plan their releases of their own software, knowing when they'll be getting a feature. In this particular case, though, he doesn't quite understand the delay as the Zend Optimizer+ isn't a change to core, it's an addition:

What is even stranger for this case is that we are just talking about an extension here. Its not a language feature, there is no engine level integration. So even if its not added to core, people can easily get Optimizer+ via PECL. So in this case we are not talking about people having to wait another 10-11 months. Don't get me wrong I think getting an opcode cache into core is awesome, but the reality is that shared host users will probably still not have access to it [...] and the rest can still get it, albeit with a bit more effort.
tagged: predictable release cycle zendoptimizer opcode pecl extension opinion

Link:

Zumba Engineering Blog:
Some CakePHP optimizations
Nov 07, 2012 @ 09:31:20

For those out there using the CakePHP framework to create your applications, you might be interested in these quick tips from Juan Basso on the Zumba Engineering Blog for both the architecture and actual code to optimize the performance of the app.

Our site and system has a lot of throughput and it make us use more instances and try to reduce the load in every part. It makes the company happy (save money) and also make the customer happy (faster load). On this article I will go over few things in terms of architecture and some code changes/strategies that could make your application faster as well.

Some of the recommendations include:

  • Installing the APC/opcode caching to help save execution time
  • Avoiding as many network requests as possible
  • Use local file/data caching
  • Using the "requestAction" inside controllers with its built-in caching
tagged: cakephp optimize caching apc opcode file resource

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