This webinar covers both introductory as well as advanced topics related to ElastiCache and is intended for current memcached users as well as those already using ElastiCache. During this session we will go over various scenarios and use-cases that can benefit by enabling caching, discuss the features provided by ElastiCache, and review best-practices, design patterns, and anti-patterns related to ElastiCache. The webinar will also include a demo where we enable ElastiCache for a web application and show the resulting performance improvements.

1. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Accelerating Application Performance
Using In-Memory Caching in AWS
Omer Zaki (omerz@amazon.com)
Shakil Langha (slangha@amazon.com)

2. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Agenda
Caching Overview
Memcached
Amazon ElastiCache
Use Cases & Design Patterns
Demo

3. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
A Typical Web Application
Web
Server
DB
Server
Users
Web Server
Database Server

4. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
A Typical Web Application
Web
Server
DB
Server
Step 1: Users hit your web app

5. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
A Typical Web Application
Web
Server
DB
Server
Step 1: Users hit your web app
Step 2: The Web App queries the Database

6. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
A Typical Web Application
Web
Server
DB
Server
Step 1: Users hit your web app
Step 2: The Web App queries the Database
Step 3: The Database returns the Result

7. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
A Typical Web Application
Web
Server
DB
Server
Step 1: Users hit your web app
Step 2: The Web App queries the Database
Step 3: The Database returns the Result
Step 4: The Web App returns the Page

8. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
A Typical Web Application
Web
Server
DB
Server
Step 5: You scale Web and Database Servers
Web
Server
DB
Server
Web
Server
DB
Server

9. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
A Typical Web Application
Web
Server
DB
Server
Step 5: You scale Web and Database Servers
Step 6: Now What?
Web
Server
DB
Server
Web
Server
DB
Server

10. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
A Typical Web Application
Web
Server
DB
Server
Step 5: You scale Web and Database Servers
Step 6: Now What?
Step 7: Use a Cache
Web
Server
Web
Server
DB
Server
Cache

11. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
What is a Cache?
Component that stores frequently accessed data in memory
Requests for data in the cache are returned faster
Benefits:
• Faster responses for cached data
• Reduces load on your database

12. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Why Use a Cache?
For a majority of web applications, workloads are read
heavy
• Often as high as 80-90% reads vs. writes
Memory is orders of magnitude faster than disk
• Latency can be reduced from milliseconds to microseconds

13. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Caching: An Example
Example: Get John Smith’s Phone Number
First Time:
Cache = {}
Step 1: Look in the cache. It’s empty; ‘cache miss’
Step 2: Get the value from the DB; update the cache

14. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Caching: An Example
Example: Get John Smith’s Phone Number
Second Time:
Cache = {‘John Smith’ : ‘206-555-1212’}
Step 1: Look in the cache. Return the result; ‘cache hit’
Step 2: Until John’s number changes, we don’t hit the DB

15. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Caching: An Example
Example: John gets a new phone number – ‘415-555-1212’
Cache Invalidation:
Cache = {‘John Smith’ : ‘206-555-1212’} (out of date)
Step 1: Update Database with John’s new number
Step 2: Update the cache with John’s new number
Cache = {‘John Smith’ : ‘415-555-1212’}

16. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Caching: Pros & Cons
Pros
• Speed up applications, especially if they are read-intensive
• Reduce load on your database servers
Cons
• Requires a change in application architecture
• Application needs to ensure data in the cache is current

17. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Agenda
Caching Overview
Memcached
Amazon ElastiCache
Use Cases & Design Patterns
Demo

18. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Memcached: Overview
Memcached (read: mem-cache-dee)
Free, open-source, high-performance, in-memory key value
store
Developed for LiveJournal in 2003
Used by many of the worlds top websites:
• YouTube, Facebook, Twitter, Pinterest, Tumblr, …

19. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Memcached: Architecture
Servers with key-value associative
arrays
Client software populates the array
and queries it
Clients know about all the servers
Servers don’t communicate with
each other
Least Recently Used
No persistence
Source: http://architects.dzone.com/news/notes-memcached

20. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Memcached: Storing Data
Stores arbitrary data
• HTML snippets
• Database query results
• Computed results
Keys are limited to 250 bytes
Values are limited to 1Mb

21. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Agenda
Caching Overview
Memcached
Amazon ElastiCache
Use Cases & Design Patterns
Demo

22. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Amazon ElastiCache
Web service that lets you easily
create and use cache clusters in
the cloud
100% Memcached compatible
Managed, scalable, secure
Pay-as-you-go, and flexible, so
you can add capacity when you
need it

23. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Amazon ElastiCache: Benefits
Easy to
Deploy
Deploy multi-
node cache
clusters with a
few button
clicks or API
calls
Easy to
Migrate
100%
Memcached
compatible
Existing code
will work when
you update
server lists
Easy to
Administer
Automatically
replaces failed
nodes and
patches
software
CloudWatch
enables you to
monitor cache
performance
metrics
Easy to
Scale
Add or remove
cache nodes
with a few
button clicks,
or API calls
Easy to
Secure
Works well
with EC2 and
DB Security
groups which
means the
cache is
secure

24. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Agenda
Caching Overview
Memcached
Amazon ElastiCache
Use Cases & Design Patterns
Demo

25. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Common Use Cases
Social networks
Gaming
Media and News Sites
Q&A Portals
E-Commerce
Recommendation Engines
Mobile app back-ends

26. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Sample Deployment: Gaming
Auto-scaling front end
Amazon ElastiCache
Amazon RDS
Amazon S3
Amazon CloudFront

27. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Common Design Patterns
Database offloading
• Allows web apps to scale independent of backend data tier
Session management for transient data
• Increment/decrement high scores for gaming environments
In memory storage for difficult / time consuming tasks
• Picture ids for all pictures tagged with a particular keyword

28. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Anti-Patterns
Build application logic assuming cache
hit latency
Put objects into cache without Time-
To-Live set (TTL)
Sequentially sending single operations
to cache (avoiding usage of batched
operations)
Configuring Memcached client to use
Redistribute Failure mode for
ElastiCache cache nodes
Resolving DNS only once.
Failing application request for cache
miss.
Using Memcached as a durable store.
Not designing application error paths
regarding cache operations
• Connection timeouts, operation
timeouts, etc.

29. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Best Practices
Share Memcached Client objects in application
Use TTLs (short TTLs)
Consider Memory for Connections Overhead
Use CloudWatch Alarms / SNS Alerts
Use Consistent Hashing
Use Auto Discovery

30. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Agenda
Caching Overview
Memcached
Amazon ElastiCache
Use Cases & Design Patterns
Demo

31. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Adding Caching to a Web App
Existing Web App running in EC2
• Using RDS MySQL database
Steps
1. Create ElastiCache Cluster with 2 cache nodes
2. Modify the Web App to use Caching

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Create Cache Cluster: Cluster Specification

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Create Cache Cluster: Security / Parameters

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Create Cache Cluster: Cluster Created

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Modify Web App to use Caching
Initialization
import memcache
CACHE_NODES = ['hostname1:port1',
'hostname2:port2']
mc = memcache.Client(CACHE_NODES)
Key Lookup
KEY = "demo.key"
KEY_EXPIRY_SECONDS = 60
value = mc.get(key)
if (not value):
value = getDataFromExistingLogic()
#retrieve from existing app logic -
database, filesystem, other processing
mc.set(key, value, time =
KEY_EXPIRY_SECONDS)
return value

36. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Web App with Caching

37. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Performance Improvement
Performance run using Multi-Mechanize
• Runtime: 600 seconds
• Time-series interval: 5 seconds
• ElastiCache usage configured to start at 200 seconds mark

38. © 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified or distributed in whole or in part without the express consent of Amazon.com, Inc.
Performance Improvement

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Questions