Memcached and the Rise of the Dynamic Web

September 2009

Presented by:

Bill Takacs – Director, Product Management

2 : Copyright 2009 Gear6 Inc.

Agenda

•!Rise of the dynamic web!

•!The web architecture!

•!The evolution of a dynamic site and Memcached!

•!Gear6 solution!


The Web: What’s Changed?

•!Population!

•!Tra"c!

•!Content and applications!


Web Growth: Population

Forrester: 2.2 billion people online globally by 2013


Web Growth: Traffic

Cisco: “Annual global IP traffic

will exceed two-thirds of a zettabyte

(667 exabytes) in four years” [by 2013]

Source: Cisco Visual Networking Index,

9 June 2009


Web Growth: Application & Content

Entertainment!

Social Networking!

Media!

Communication!

Community-generated content!

Growth can be painful

(VERY)

But growth can be

painful


Web Architecture

CDN!

Clients

Internet Storage

Net

Interface

Proxy

Load

Balancer

Web Stack

Web

Serv

ers#

Ap

ache, N

gin

x,

Lig

http

d!

Ap

p

Serv

ers!

PH

P, Ja

va, R

ails

, C,

Perl, P

yth

on!

Data

base!

MySQ

L,

Postg

reSQ

L !

!! Most sites (over 65%) based on LAMP or JAVA

!! Industry standard servers replaced proprietary SMP

!! Shift to Dynamic Content puts strain on origin sites


What to do?


New Caching Architecture for Scaling Out

CDN!

Clients

Internet Storage

Net

Interface

Proxy

Load

Balancer

Web Stack

Web

Serv

ers#

Ap

ache, N

gin

x,

Lig

http

d!

Ap

p

Serv

ers!

PH

P, Ja

va, R

ails

, C,

Perl, P

yth

on!

Data

base!

MySQ

L,

Postg

reSQ

L !

Cache Servers memcached


Memcached: Pillar of Web 2.0 Architecture

“Everything runs #from memory#in Web 2.0”!

Evan Weaver, Twitter, March 2009!


The Fix: Memcached

“A high performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by

alleviating database load”!

•!Big hash table!

•!Created by Danga Interactive for LiveJournal!

•!Significantly reduced database load!

•!Perfect for web sites with high database load!

•! In use by Facebook, Twitter, MyYearbook, others!


Evolution of a Dynamic Site #1 A day in the life of a growing web service

•! Event: Site has growth in number of users/sessions/page views/apps causing excessive read load on DB!

•!Action: Replicate Database (and/or add more app servers)!

MySQL

App Server App Server App Server

write!

MySQL


write!

MySQL

write! …




•! Event: Individual caches on the app/db servers are overwhelmed from chaotic/non-deterministic content access!

•!Action: Add memcached server on servers with underutilized memory resources… results in even fewer reads to database!

MySQL


write!

MySQL

write! …


MySQL


write!

MySQL

write! …

App Server App Server App Server memcached memcached memcached

memcached memcached memcached


MySQL


•! Event: Memcached needs more memory resources than what is available on other (shared) servers!

•!Action: Move memcached servers to dedicated servers!

MySQL


write!

MySQL

write!

…



write!

MySQL

write! …

App Server App Server App Server memcached memcached memcached

memcached memcached

memcached memcached memcached

memcached

…


What Memcached is NOT:

Fault-tolerant or highly available!

A large object cache!

Application-specific!

A database!

A persistent data store!


Memcached: Best Practices

•!Use with MySQL :-)!

•!Use on 64-bit servers!

•!Cache “expensive operations”!

•!Cache bi-directionally (R/W)!

•!Design to withstand failures gracefully!

•!Use consistent hashing!

•!Careful with numbers of connections!

»!Peak!

»!Transitions!

•!Evictions!»!Segment Memcached

data into separate pools!

•!Optimize sizing: Instances and pools!

•!Instrumentation!


Memcache Use Cases

Site Type Repeatable Use

Social networking Profile caching

Content aggregation HTML/page caching

Ad targeting Cookie/profile tracking

Gaming and entertainment Session caching

Location-based services DB query scaling

Relationship Session caching

E-commerce Session and HTML caching


Use Case Example: Session Management

•!4m+ daily visitors!

•!15k hits/sec!

•!6k updates/sec!

•!Tens of thousands concurrent connections!

•!Session tracked and ads are placed in accordance to session!


Hadoop!

Recommendations on

User webpages

Load Balancer Load Balancer

Load Balancer

Webserver / php

User Targeting Service

Thin/fast memcache

Client layer (reads)

Update processing

(writes)


Thin/fast memcache


Update processing

(writes)


Thin/fast memcache


Update processing

(writes)

Map/Reduce Jobs

Data processing

User profile updates

Ad-Hoc Analysis

Memcache repopulation

(bulk updates, recovery)

User targeting data

From logs and other

systems

“Lazy” Updates

Bulk/batch

updates

Use Case Example:

User Targeting Engine

Memcached pool!

Reports!


Useful Memcached Tools

advanced reporter!

wireshark!

brutis!

statsproxy!

cacti!Graph and analyze Memcached statistics!

View bu$ered Memcached stats in your browser!

Size and test changes to memcache clusters!

Dissect and analyze Memcached network tra"c!

Track hot keys and clients in Memcached!


Statsproxy + Cacti Templates

To use the cacti

templates for

memcached with statsproxy, you

either need to

modify the

templates to use

port 8080 or change the

statsproxy config to

use port 11211


•! First and leading provider #of Memcached solutions!

•! Memcached solution including!

•! High density!

•! High Availability!

•! Advanced memory #management!

•! Enhanced reporting#capabilities !

•! Support for multi-tenancy!

•! Disruption free #software upgrades!

•! 100% client compatible!


Questions?

Thank you for attending our webinar!

“Memcached and the Rise of the New Dynamic Web” !

www.gear6.com!and please visit our web site at:!


References

•! Danga.com!

•! Highscalability.com!

•! Dev.gear6.com!

•! Groups.google.com/group/memcached!

•! Code.google.com/p/memcached!

•! Twitter.com/gearsix!

•! Cacti.net!

•! Wireshark.org!

•! http://dev.mysql.com/doc/mysql-ha-scalability/en/ha-memcached-

using-deployment.html!

•! http://dev.mysql.com/doc/mysql-ha-scalability/en/ha-memcached-using-hashtypes.html!

•! http://jayant7k.blogspot.com/2009/04/memcached-replication.html!

•! http://www.lexemetech.com/2007/11/consistent-hashing.html!

•! http://www8.org/w8-papers/2a-webserver/caching/paper2.htmlhttp://www.last.fm/user/RJ/journal/2007/04/10/rz_libketama_-_a_consistent_hashing_algo_for_memcache_clients!

•! http://bazaar.launchpad.net/~libmemcached-developers/libmemcached/

trunk/revision/539!

Memcached and the Rise of the Dynamic Web

Technology

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