ExpressionEngine Performance & Optimization:

Laying a Solid Foundation (& Caching)CHRIS WELLS – CEO – NEXCESS.NET LLC

The Ambassador Bridge (USA/Canada)

• Completed in 1929 (Longest suspension bridge worldwide)

• Busiest international trade crossing in North America!

• Carries 25% of all US/Canadian merchandise trade

• Drive south to go north?• Owned by a private citizen !?

The Ambassador Bridge (USA/Canada)

Detroit, MI USA

Windsor, Ontario Canada

The Detroit-Windsor tunnel is cool too!

Today’s Topics• Why is the foundation important?

• MySQL choices

• PHP & the Apache/PHP hand-off

• Caching overview

• ExpressionEngine internal caching

• ExpressionEngine (modified) template caching

• Caching with CE cache

• Caching the caches with Varnish

• Clustering ExpressionEngine

Perspective• Nexcess is a 13 year old company

• 90 employees (customer service being the largest contingent)• Staff of 48 in support/customer service (all U.S./Michigan based)

• Wholly owned data centers in the U.S.

• Partner data centers in the U.K. and Australia

• For better or worse we are not designers

• Hosting company / infrastructure view of the system

• We often are developers but again with a view that differs from web application developers

Why Care About The Foundation?• Security, Stability, Performance

• Proper security/stability/performance permeates to the bare metal

• Do what you can with the access you have, ask questions about what is out of reach

• Assume nothing

The Foundation • Linux

• Reboot-less updates (including on the kernel level)

• Apache (of Nginx)

• MySQL (Percona Server)

• PHP

• ExpressionEngine

MySQL (For Very High Traffic Sites)

• Don’t use MySQL!• Use Percona Server!

• Percona Server is a simple MySQL replacement

• Percona is much better under stress

• Percona has a very good implementation of InnoDB tables (called XtraDB)

• Use InnoDB!• Row (instead of table) level locking

• Tune InnoDB for your CPU / RAM configuration – it matters!

• A sample my.cnf is on our github account: https://github.com/nexcess/ee-whitepaper-v1-configs

• MariaDB is an alternative as well although we haven’t benchmarked it (yet)

PHP Basics• Use APC (as an opcode cache only)

• apc.shm_size = 256M (at least)

• apc.num_files_hint = 10000 (at least)

• apc_stat = 0 (for production)

• Bump PHP’s memory_limit (128M works well)

• Turn off open_basedir• Leaving it on kills the realpath cache

• Security concerns can be handled with tighter file system security

• Use a recent version of PHP (5.4.x+)• 5.4.x is fast!

• 5.4.x has a much lower memory footprint than prior versions

• Invoke PHP in the right way

The PHP Hand-off• This handoff is critical for both security and performance

• Apache + mod_php• Runs as webserver user

• Unified mega-process

• Apache + suPHP / phpSuEXEC• Runs as you

• Expensive to create

• Apache + PHP-FPM• Runs as you

• Cheap to use

• Scales more efficiently than all of the above

The PHP Hand-off –

Apache+mod_php

The PHP Hand-off –

Apache+suExec[PHP]

The PHP Hand-off – Apache+PHP-

FPM

File System Permissions Matter

YES! Do This!!

File System Permissions Matter

666 and 777 settings are both evil!

Fixing File System PermissionsFix it!! (relative to your web root)

1.Own your files / directories

find \-exec chown eecms.eecms {} \;

2.Make browsing directories for others non-trivial.

find -type d \-exec chmod 711 {} \;

3.Make sure the webserver can read it all

find -type f \-exec chmod 644 {} \;

4.PHP scripts are for your eyes only

find -type f -name “*.php” \-exec chmod 600 {} \;

NOTE – config.php and database.php are 600! This is good!

NOTE2 – This only works in a PHP-FPM or suPHP world!

NOTE3 – You may need root level assistance to achieve this

chmod

On What?

Means

711 Directories

You can do anything, others can ‘list’

644 Files You can read/write, others can read

600 Files You can read/write, others have no access

The Need For Caching• Any DB (or file) based CMS introduces complexity

• More complexity means slower page loads

• A single sub-optimal query can kill a site’s performance

• This all sounds pretty dire

• More queries does not necessarily mean slower page loads!

• Developers need strike a balance between speed, complexity and maintainability

• Caching can fix it!!

ExpressionEngine Built-in Caching• Tag Caching

• Caches tag results (to disk)

• Good for pinpointing bad tags/queries and caching them on the spot

• BUT… The 1st instance of the tag will still be slower

• Template Caching• Caches entire templates (to disk)

• Dynamic Channel Query Caching• Caches parts of the channel entries (to disk)

• MySQL’s query cache can help here too

• Query Disabling• More a pruning measure than caching but still effective

Benchmarking Caching Strategies• “Agile Records” default install

• 100,000 additional news entries (thanks EllisLab!)

• This is an atypically sized ExpressionEngine site (i.e. BIG)• We’re trying to push the limits!

• Dell R410 (What equates to our EEP-400 offering)• Dual E5620 quad core CPUs

• 16GB RAM

• 4 x 147GB 15k SAS drives (RAID 10)

• Software Snapshot• ExpressionEngine 2.7.0

• CentOS 6.4 (64-bit)

• PHP 5.3.24 (5.4 would have been faster)

• Percona Server 5.5

A warm cache makes a big difference

Cache “warming” in progress

Avg. response time goes from ~8 to

~0!

Transactions / sec go from

7 to ~80!

Concurrency = 30900 Random URLs

200 concurrent

users @ ~260

trans/sec

Server’s physical

resources exhausted

Nexcess’ Memcache Patch• Replaces the on-disk portions of ExpressionEngine’s

default caching with memcache• No code (customer) code changes needed

• Memcache is an in-memory data store• Key/value based

• Very fast compared to disk

• Avoids file-system IO limitations• File locking

• Read/write performance

• Created as a stop-gap on higher traffic sites

• Open source – BUT BE CAREFUL!

~8 transactions /

sec faster

Concurrency = 30900 Random URLs

Much better high traffic

performance!

Causing Effect’s Cache Plug-in• Created by Aaron Waldon of Causing Effect

• Very flexible cache addition to ExpressionEngine

• Memory or file-based back-end, with failover• Leverage fast memory caching

• Fall back to file based caching if any daemon fails

• Full static page capability• Good for OMG events

• Benchmarks are done using the full page static caching• Given EE’s flexible nature this was the easiest/best test

EE’s template caching was

~80 trans/sec

Our patch raised this to

~88

CE Cache’s static caching

hits ~100.

Concurrency = 30900 Random URLs

Our patch peaked @

~360 trans/secAaron’s hits a

pretty consistent

500 trans/sec

Caching the Caches With Varnish• Varnish is a caching HTTP reverse proxy (i.e. web

application accelerator)

• Varnish caches entire rendered pages in memory• Once a page is in Varnish it bypasses:

• The webserver (Apache)• The web application (PHP/MySQL)• And everything else lower in the stack!

• Application level caching still matters!• Cache misses hit the application

• Using Varnish with even brief (1 minute or less) timeouts can still help

• SO JUST TURN IT ON FOR MY SITE ALREADY!!

All previous were ~80 –

100trans/sec

Varnish is ~550

Concurrency = 30900 Random URLs

EE template caching

The Nexcess patch

CE Cache Static Files

Varnish @ ~1000 trans/sec

Pushing ExpressionEngine Further• Pitfalls to avoid

• File synchronization

• File-based caching causes flock() contention

• Clustering• Load balanced over many web application servers

• Unified in-memory caching with dedicated caching server

• Varnish front-end servers

• DB clustering

• THE FOG…• Hybrid cloud solution

• Provides on-demand expansion where it counts

• Offload PHP-FPM to the Fog

Final Thoughts• Detroit is not so bad. Lots of inbound Canadian and outbound

U.S. merchandise passes through it at least!

• Don’t build your house on a rock pillar in the ocean

• 666 & 777 are evil

• PHP-FPM is the way to go

• Use Percona Server over MySQL and InnoDB on high traffic sites

• Caching is good – decide which works for you• Choose the fastest cache mechanism that makes sense

• In memory caches are almost always the best option

• Varnish is good but requires TLC

• The sky is the limit when it comes to ExpressionEngine performance!

More Information• Our github repository is at:

https://github.com/nexcess

• Our new performance whitepaper is available at:

http://www.nexcess.net/eecms-best-practices-whitepaper

Thank You!

Questions?

Chris Wells – clwells@nexcess.net