Olivier Dolbeau, Benjamin De Bernardi "25+ millions members in 22 countries, how to scale with Symfony 2?"

PHP Frameworks Day 2016 - 25+ million members in 22 countries; How to scale with Symfony2 @odolbeau & @genes0r
25+ million members in 22 countries;
How to scale with Symfony2?
Benjamin De Bernardi - Olivier Dolbeau

@genes0r
Lead Engineer
Benjamin De Bernardi

Olivier Dolbeau
@odolbeau
Web Architect

100€ 25€ 25€ 25€
100€ 25€

15M
20M
10M
5M
1M
2015201420132012201120102009
25M
membersworldwide
Over 25 million members and growing
1.5 million+
joining each month

1. The past
2. Why symfony?
3. How?
○ How to deal with 22 countries?
○ Why do we love the EventDispatcher?
○ Performance & asynchronous
○ Doctrine
4. Traps
5. Here & now
Talk overview:

The past
1

v1.0
2005-2006

v2.0
2008-2011
(2014)

2010
New countries
2011 2012

3 770 lines of code
69 functions
926 lines for the longest one.
lib.trip.php

Homemade framework

NO TESTS

v3.0
2011 - today

2012 2013 2014 2015
New countries

Why Symfony?
2

Huge community.

Attract new people

How?
3

22 countries, how can we manage
specificities?

➔ One codebase for each country?
➔ Conditions everywhere in the code?
➔ Configuration and Context?
22 countries: how can we manage specificities?

Web request Listener
Symfony parse & build a
Request object
Build Context from
configuration and Request
Response
22 countries: Configuration & Context

1 file for each country
100+ configuration keys
Inheritance
Toggling of features
Metadata
Configuration:

Get config from a controller:

Get config from the view:

Lot of code, how to keep events clean?

➔ Symfony built-in EventDispatcher

EventDispatcher how it works:
Event DispatcherEvent
Listener
Listener

User A rates User B:
Event Dispatcher
New
Rating

Event Dispatcher
New
Rating
Grade
Listener
Recalculate the grade
of both users

Event Dispatcher
New
Rating
Grade
Listener
Moderation
Listener
Ask for content
verification

Sending the event:
● Sent from anywhere

Registering a listener:
● Update a configuration file

Listening the event:
● Inside a registered listener

+ Perfect to decouple code inside the app.
+ Small listeners, easy to understand, to test.
+ Easy to dispatch events outside application.
- Sometimes, hard to understand the flow.
- Need tools/rules to keep a common logic.
Dispatching events Pros/Cons

■ Avoid Entities
■ Keep listener small and dedicated to a single task
■ Limit dependencies
Dispatching events one last thing:

High traffic, how to improve
performance?

Problem:
The website is a bit slow

Solution:
All side tasks can be done asynchronously

Solution:
All side tasks can be done asynchronously
Tasks:
● Find a tool to transmit messages
● Create workers
● Use the event dispatcher

Asynchronous jobs everywhere.
● Performance
● Job splitting

Dispatch Event with the EventDispatcher.
● Listened with RabbitMQ or internal Listeners

Check eventName &
event interface
Dispatch the event
in the application
Decorated EventDispatcher.
Publish to
RabbitMQ

Send an Email
● Built using the User context in a dedicated worker

+ Perfect to decouple code
+ Small workers, easy to understand
+ Easy to dispatch events outside application
+ Separate projects & deployment
+ Scalable!
- Learning curve
- Need tools/rules to keep a common logic
- Hard to test a complete flow with mock/stubs
- Mapping is time consuming
Asynchronous event & process Pros/Cons

129 workers
Mail
SMS
Publication
Push
Indexation
Image
resizing
Alerts
Profile
completion
I love
workers!
Payment

Asynchronous workers:
Infrastructure:
■ PHP
■ Supervisord
Code:
■ Symfony command inside the main app
■ Standalone app + Symfony components

Asynchronous workers, Symfony:
+ Access to Entities
+ Every already defined services
- Entire Symfony
- Not dedicated
- Deployed along the website
- Not the main goal of Symfony
- High memory usage

Asynchronous workers, Standalone:
+ Dedicated to a single task/type
+ Maintainable small code
+ Deployed independently
+ Easily created & tested
- Component splitting from the codebase
- More monitoring

About Doctrine...

It’s not a troll.

Code fast!

Code well?

Queries from
the view!
Hard to control
cache strategy
No integrity
check.

Doctrine Pros/Cons
+ Quick to bootstrap a new project
+ Quick to code a small project
- Hard to respect MVC
- Hard to deal with cache
- Hard to deal with integrity problems in DB
- Not made to decouple code (relations).
- Not made to scale.

We fell in traps...
4

Never pimp your kernel!

Before
Environment
Debug?

Before
After
Branding Media
Environment
Debug?

Put everything in
the same place can be
dangerous!

This is our
application.
This is our
business code.

Don’t mess with
your tools!

We fell in traps...

We had parachutes!

Problems solved?
+ Use symfony only as a tool
+ Work a lot on onboarding
+ Try to decouple everything with components
- We still have one big application
- As everyone, we lack of documentation

5

40 269
Commits
There are “only” 18 952 commits for symfony/symfony

561 851
NCLOC
There are “only” 278 909 NCLOC for symfony/symfony

~ 20
minutes to run all the
unit/functional tests

~ 30
minutes to deploy the application

Too big!

We’re working
on it! ;)

We’re hiring!In Paris & Warsaw!http://blbl.cr/dreamjobs

Olivier Dolbeau, Benjamin De Bernardi "25+ millions members in 22 countries, how to scale with Symfony 2?"

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