CakePHP

[engineering]

PHP 7 at Tumblr

At Tumblr, we’re always looking for new ways to improve the performance of the site. This means things like adding caching to heavily used codepaths, testing out new CDN configurations, or upgrading underlying software.

Recently, in a cross-team effort, we upgraded our full web server fleet from PHP 5 to PHP 7. The whole upgrade was a fun project with some very cool results, so we wanted to share it with you.

Timeline

It all started as a hackday project in the fall of 2015. @oli and @trav got Tumblr running on one of the PHP 7 release candidates. At this point in time, quite a few PHP extensions did not have support for version 7 yet, but there were unofficial forks floating around with (very) experimental support. Nevertheless, it actually ran!

This spring, things were starting to get more stable and we decided it was time to start looking in to upgrading more closely. One of the first things we did was package the new version up so that installation would be easy and consistent. In parallel, we ported our in-house PHP extensions to the new version so everything would be ready and available from the get-go.

A small script was written that would upgrade (or downgrade) a developer’s server. Then, during the late spring and the summer, tests were run (more on this below), PHP package builds iterated on and performance measured and evaluated. As things stabilized we started roping in more developers to do their day-to-day work on PHP 7-enabled machines.

Finally, in the end of August we felt confident in our testing and rolled PHP 7 out to a small percentage of our production servers. Two weeks later, after incrementally ramping up, every server responding to user requests was updated!

Testing

When doing upgrades like this it’s of course very important to test everything to make sure that the code behaves in the same way, and we had a couple of approaches to this.

Phan. In this project, we used it to find code in our codebase that would be incompatible with PHP 7. It made it very easy to find the low-hanging fruit and fix those issues.

We also have a suite of unit and integration tests that helped a lot in identifying what wasn’t working the way it used to. And since normal development continued alongside this project, we needed to make sure no new code was added that wasn’t PHP 7-proof, so we set up our CI tasks to run all tests on both PHP 5 and PHP 7.

Results

So at the end of this rollout, what were the final results? Well, two things stand out as big improvements for us; performance and language features.

Performance

When we rolled PHP 7 out to the first batch of servers we obviously kept a very close eye at the various graphs we have to make sure things are running smoothly. As we mentioned above, we were looking for performance improvements, but the real-world result was striking. Almost immediately saw the latency drop by half, and the CPU load on the servers decrease at least 50%, often more. Not only were our servers serving pages twice as fast, they were doing it using half the amount of CPU resources.

These are graphs from one of the servers that handle our API. As you can see, the latency dropped to less than half, and the load average at peak is now lower than it’s previous lowest point!

Language features

PHP 7 also brings a lot of fun new features that can make the life of the developers at Tumblr a bit easier. Some highlights are:

Scalar type hints: PHP has historically been fairly poor for type safety, PHP 7 introduces scalar type hints which ensures values passed around conform to specific types (string, bool, int, float, etc).

Return type declarations: Now, with PHP 7, functions can have explicit return types that the language will enforce. This reduces the need for some boilerplate code and manually checking the return values from functions.

Anonymous classes: Much like anonymous functions (closures), anonymous classes are constructed at runtime and can simulate a class, conforming to interfaces and even extending other classes. These are great for utility objects like logging classes and useful in unit tests.

Various security & performance enhancements across the board.

Summary

PHP 7 is pretty rad!

[cakephp]

We moved our platform to php 7 a few months ago. Tumblr was a much bigger effort of course. I’m glad to see that the results.

[thingsprogrammersshout]

Things Programmers Shout #544

“WHY THE F*CK DOES THIS NOT WORK?” … Hours Later… “I’M SUCH AN IDIOT…”

// submitted by anonymous

[alamantus]

Oh look, it’s every problem I’ve ever had while coding!

[cakephp]

Naming Controllers, Models, Tables etc

I find it strange that CakePHP(1.x, 2.x), Ruby and others have spent so much time and effort worrying about the use of singular and plural names for controllers, tables and models. Why is it necessary to name the controller Recipes and the model Recipe and the table Recipes? Are we really going to name a controller Octopi, and the model Octopus?  Who came up with this idea that this HAD to be done? Does it add anything of value to an application? I suggest that it does not.  If anything it only adds confusion. It is yet another facet that a programmer has to learn and remember.  To me, this convention is merely some sort of programmer OCD created by some who cannot bear to see two pencils that are not exactly even in length or that two glasses have exactly the same amount of liquid.

When I look at the CakePHP source, I am amazed at how much code had to be written to support this. What a waste.

Programmers look at the URL and seem to care what is there. It’s like seeing the matrix. Non-programmers do not care what is in the URL. If it says Recipe or Recipes they do not care.  Furthermore, browsers are starting to not even show the URL at all unless the user wants to see it. So the idea that the controller should be named Recipes because it shows multiple recipes has little or no meaning.  And users do not pay much attention to that anyway.

In my own project, I decreed that all elements will be named in the singular. The controller, model and table will all be named Recipe. No exceptions. Our transaction table is named Transaction and its controller is named TransactionController.

In order to make this work, it is necessary to turn off CakePHP’s inflection. Add the following to app/Config/bootstrap.php:

Inflector::rules('singular', array('rules' => array('/(.*)/' => '$1'), 'irregular' => array(), 'uninflected' => array())); Inflector::rules('plural', array('rules' => array('/(.*)/' => '$1'), 'irregular' => array(), 'uninflected' => array()));

This establishes an override rule that maps anything to itself for singular to plural or plural to singular conversions. CakePHP is still doing the conversion but the result is the same as whatever is input. Ideally, I would prefer to totally disable this but that seems like it would require changing the CakePHP core and I don’t want to do that.

[cakephp]

Naming Class Files for Autoloading

In case you need it, there’s a specification for how to name files, classes and directories for autoloaders.

http://www.php-fig.org/psr/psr-4/

[cakephp]

CakePHP 3.0 took over the CakePHP site.  3.0 is fully underway now. Also, they plan on back porting some features and fixes to 2.x. Way to go guys.

[cakephp]

PHPUnit And CakePHP 2.x

CakePHP 2.x is not compatible with the latest version of PHPUnit.  They advise developers to install PHPUnit using PEAR.  However, PHPUnit is discontinuing support for PEAR by the end of 2014. PEAR installation may work now, but we need a longer term solution as CakePHP 2.x.

We all want things to be as little hassle as possible and that includes me.

PHPUnit's recommended installation processes will not work with CakePHP with the exception of Composer. Composer installs PHPUnit inside the CakePHP app so it isn't a global install. 

I went through the process of manually installing PHPUnit from github. I won't go through the entire process here because no one will intentionally want to do that.

I made a repo on Bitbucket that has all the files for PHPUnit 3.7 including dependencies.

[email protected]:ryantxr/cakephpunit.git

Installation (on OSX) using this repo is as follows.

git clone [email protected]:ryantxr/cakephpunit.git

cd cakephpunit

sudo mkdir /usr/local/share/php (if it does not exist)

sudo cp -r * /usr/local/share/php

Make sure that /usr/local/share/php is in your PHP include_path in php.ini

include_path=/usr/local/share/php