Rome, 28 October 2016

Scaling Symfony apps

WHO AM I?

Matteo Moretti

CTO @

website: madisoft.ittech blog: labs.madisoft.it

Scalability

It’s from experience.

There are no lessons.

Nuvola

● > 3M HTTP requests / day● ~ 1000 databases● ~ 350GB mysql data● ~ 180M query / day● ~ 25M of media files● ~ 4.50TB of medis files● From ~5k to ~200k sessions in 5 minutes

Scalability

Your app is scalable if it can adapt to support an increasing amount of data

or a growing number of users.

“But… I don’t have an increasing load”

(http://www.freepik.com/free-photos-vectors/smile - Smile vector designed by Freepik)

“Scalability doesn’t matter to you.”

(http://www.freepik.com/free-photos-vectors/smile - Smile vector designed by Freepik)

“I do have an increasing load”

(http://www.freepik.com/free-photos-vectors/smile - Smile vector designed by Freepik)

Your app is growing

But… suddenly…

Ok, we need to scale

Scaling… what?PHP code?

Database?

Sessions?

Storage?

Async tasks?

Everything?

Can Node.js scale?

Can Symfony scale?

Can PHP scale?

Scaling is aboutapp architecture

App architecture

How can you scale your web server if you put everything inside?

Database, user files, sessions, ...

App architecture / Decouple

● Decouple services● Service: do one thing and do it well

App architecture / Decouple

4 main areas

1. web server2. sessions3. database4. filesystem

There are some more (http caching, frontend, queue systems, etc): next talk!

Web server

Many small webservers

(scale up vs scale out)

Web server

NGINX + php-fpm

PHP 7

Symfony 3

Web server / Cache

PHP CACHE

SYMFONY CACHE

DOCTRINE CACHE

Web server / PHP Cache

Opcache

Bytecode caching

opcache.enable = On

opcache.validate_timestamps = 0

https://tideways.io/profiler/blog/fine-tune-your-opcache-configuration-to-avoid-caching-suprises

PHP code / Symfony cache

● Put Symfony cache in ram ● Use cache warmers during deploy

releaseN/var/cache -> /var/www/project/cache/releaseN

“/etc/fstab”

tmpfs /var/www/project/cache tmpfs size=512m

PHP code / Doctrine cache

● Configure Doctrine to use cache● Disable Doctrine logging and profiling on prod

doctrine.orm.default_metadata_cache:type: apc

doctrine.orm.default_query_cache:type: apc

doctrine.orm.default_result_cache:type: apc

PHP code / Cache

DISK I/O ~ 0%

Monitor

Measure

Analyze

PHP code / Profiling

XHProf

Blackfire

New Relic

PHP code / Recap

● Easy● No need to change your PHP code● It’s most configuration and tuning● You can do one by one and measure how it affects performance● Need to monitor and profile: New Relic for PHP● Don’t waste time on micro-optimization

Take away: use cache!

Sessions

● Think session management as a service● Use centralized Memcached or Redis (Ec2

or ElasticCache on AWS)● Avoid sticky sessions (load balancer set up)

Session / Memcached

No bundle required

https://labs.madisoft.it/scaling-symfony-sessions-with-memcached/

Session / Redis

https://github.com/snc/SncRedisBundle

https://labs.madisoft.it/scaling-symfony-sessions-with-redis/

Session / Redisconfig.yml

framework: session: handler_id: snc_redis.session.handler

Session / RedisBundle config

snc_redis: clients: session_client: dsn: '%redis_dsn_session%' logging: false # https://github.com/snc/SncRedisBundle/issues/161 type: phpredis session: client: session_client locking: false prefix: session_prefix_ ttl: '%session_ttl%'

Session / Redisparameters.yml

redis_db: 3redis_dsn_session: 'redis://%redis_ip%/%redis_db%'redis_ip: redis-cluster.my-lan.comsession_ttl: 86400

Session / Recap

● Very easy ● No need to change your PHP code● Redis better than Memcached: it has persistence and many other features● Let AWS scale for you and deal with failover and sysadmin stuff

Take away: use Redis

Database

Aka “The bottleneck”

Database

Relational databases

Database

NOSQL db?

Database

If you need data integrity do not replace your SQL db with

NOSQL to scale

Database

How to scale SQL db?

Database

When to scale?

Database

If dbsize < 10 GB

dont_worry();

Database / Big db problems

● Very slow backup. High lock time● If mysql crashes, restart takes time● It takes time to download and restore in dev● You need expensive hardware (mostly RAM)

Database / Short-term solutions

Use a managed db service like AWS RDS

● It scales for you● It handles failover and backup for you

But:

● It’s expensive for big db● Problems are only mitigated but they are still there

Database / Long-term solutions

Sharding

Database / Sharding

Split a single big db into many small dbs

(multi-tenant)

Database / Sharding

● Very fast backuo. Low lock time● If mysql crashes, restart takes little time● Fast to download and restore in dev● No need of expensive hardware● You arrange your dbs on many machines

Database / Sharding

● How can Symfony deal with them?● How to execute a cli command on one of them?● How to apply a migration (ie: add column) to 1000 dbs?● …...

Database / Sharding

Doctrine DBAL & ORM

Database / Sharding

Define a DBAL connection and a ORM entity manager for each db

https://symfony.com/doc/current/doctrine/multiple_entity_managers.html

Database / Sharding

doctrine: orm: entity_managers: global: connection: global shard1: connection: shard1 shard2: connection: shard2

doctrine: dbal: connections: global:

….. shard1: …… shard2: …... default_connection: global

Database / Sharding

This works for few dbs (~ <5)

Database / Sharding

Doctrine shardinghttp://docs.doctrine-project.org/projects/doctrine-dbal/en/latest/reference/sharding.html

Database / Doctrine sharding

● Suited for multi-tenant applications● Global database to store shared data (ie: user data)● Need to use uuid

http://docs.doctrine-project.org/projects/doctrine-dbal/en/latest/reference/sharding.html

Database / Sharding

Configuration

doctrine: dbal: default_connection: global connections: default: shard_choser_service: vendor.app.shard_choser shards: shard1: id: 1 host / user / dbname shard2: id: 2 host / user / dbname

Database / Sharding

ShardManager Interface

$shardManager = new PoolingShardManager();

$currentCustomerId = 3;$shardManager->selectShard($currentCustomerId);// all queries after this call hit the shard where customer // with id 3 is on

$shardManager->selectGlobal();// the global db is selected

Database / Sharding

● It works but it’s complex to be managed● No documentation everywhere● Need to manage shard configuration: adding a new

shard?● Need to parallelize shard migrations: Gearman?● Deal with sharding in test environment

Database / Recap● NOSQL is not used to scale SQL: they have different purposes. You can

use both.● Sharding is difficult to implement● Need to change your code● Short-term solution is to use AWS to leverage some maintenance● Doctrine ORM sharding works well but you need to write code and

wrappers. Best suited for multi-tenant apps● When it’s done, you can scale without any limit

Take away: do sharding if your REALLY need it

Filesystem

Users upload files: documents, media, etc

How to handle them?

Filesystem

● Need of filesystem abstraction● Use external object storage like S3● Avoid using NAS: it’s tricky to be set-up correctly

Filesystem / Abstraction

● FlysystemBundle

● KnpGaufretteBundle

https://github.com/1up-lab/OneupFlysystemBundle

Filesystem / Abstractionhttps://github.com/1up-lab/OneupFlysystemBundle

● AWS S3● Dropbox● FTP● Local filesystem● ...

Filesystem / Abstraction

Configuration

oneup_flysystem: adapters: s3_adapter: awss3v3: client: s3_client bucket: "%s3_bucket%"

oneup_flysystem: adapters: local_adapater: local: directory: ‘myLocalDir’

Filesystem / Abstraction

Configuration

prod.yml

oneup_flysystem: filesystems: my_filesystem: adapter: s3_adapter

dev.yml

oneup_flysystem: filesystems: my_filesystem: adapter: local_adapter

Filesystem / Abstraction

Usage

// League\Flysystem\FilesystemInterface

$filesystem = $container->get(‘oneup_flysystem.my_filesystem’);

$path = ‘myFilePath’;$filesystem->has($path);$filesystem->read($path);$filesystem->write($path, $contents);

Filesystem / Recap

● Easy● Need to change your PHP code ● Ready-made bundles● Avoid local filesystem and NAS

Take away: use FlystemBundle with S3

Scaling / Recap

● Sessions and filesystem: easy. Do it● PHP code: not difficult. Think of it. Save money.● Database: very hard. Think a lot● Queue systems, http cache and some other stuff: next

talk but think of them as services

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