Luka Mužinić

@lmuzinic

wogibtswas.at

Client:

"do you know those widgets that we made long time ago?
we'd like tham to go live"

...

"well we don't have exact numbers, but approximately
110 million views per month"

...

"hello, HELLO?"

What is widget?

widget == banner

Stress test 1/2

Let see how many requests per second current solution can handle? Goal: ~45 req/s

7

#fail

Cache 101

code optimization

8

cache all DB queries

9

cache all Sphinx queries

12

The advice

sometimes it is better that requests don't even reach your application
- Tomicius Rasimus

The trick

make your application generate whole page into cache

whole page, <html> to </html>

Nginx

can fetch it for you

directly from memcached

or from redis

Configuration 1/2

# widget nginx + memcached
location /widget/ {
    set $memcached_key $geoip_city$uri;

    if ($arg_company != '') {
        set $memcached_key $memcached_key?company=$arg_company
    }

    default_type text/html;
    memcached_pass 127.0.0.1:11211;
    error_page 404 = @fallback;
    expires +7200;
}

Configuration 2/2

location @fallback {
    proxy_pass http://apache.application.server:8081;
    proxy_buffering off;
    proxy_redirect off;
}

Stress test 2/2

Let see how many requests per second current solution can handle?
Goal: ~45 req/s

~2010 req/s

wow. very fast. so much win.

Feedback

with keepalive https://gist.github.com/gjuric/7580148

~2035 req/s

:( values too big to have described effect

How to organize caching

our main problem was distance information

4. by IP address (approx. to much)

3. by town (1145)

2. by region (9)

1. whole Austria

Time to talk to client

How to motivate your client?

come to me with solution, don't come to me with problem

use triple constraint - cost, time, scope

quality

Final solution

VPS, 4 cores, 8 GB RAM

load barely noticeable

36 million req/month

peaks 50-60 req/second

additional memcache fallback

Add Memcache fallback

upstream memcached_backed {
    server 192.168.1.1:11211;
    server 192.168.1.2:11211;
}

# widget nginx + memcached
location /widget/ {
    memcached_pass memcached_backed;
    memcached_next_upstream error;
}

Technology alternatives

Varnish, Edge Side Includes, web accelerators...

Caching alternatives

use Geohash for key

You are not alone!

comunicate with your colleagues, devops, hosting guys, clients, bosses...

Don't bullshit!

Errors, boo-boos, tips and tricks

cache stampede & cache warm up

google analytics

keep your cache alive

Thx!

@tomyz0r, @ivedrna, @msvrtan, @goran_juric, @trikoder and many others

kthxbai!

Questions?

Something to take home

do you skip leg day?

being the best developer is not enough