Caching Strategies

Caching Strategies Michal Špaček, Skype; WebExpo 2011 , Prague @spazef0rze, www.michalspacek.cz

What the... Cache ? HDD cache, CPU cache, DNS cache, web cache, geocache

What the... Cache ? HDD cache, CPU cache, DNS cache, web cache , geocache

CLIENT (BROWSER) WEB SERVER DATABASE SERVER

HTTP level caching

Client local disk/memory cache CLIENT (BROWSER) WEB SERVER

Response headers: Expires Last-Modified ETag Cache-Control Pragma CLIENT (BROWSER) WEB SERVER

Expires: HTTP-date Expires: Sat, 24 Sep 2011 12:00:00 GMT < Expires CLIENT (BROWSER)

Expires: HTTP-date Expires: Sat, 24 Sep 2011 12:00:00 GMT > Expires CLIENT (BROWSER) WEB SERVER

Last-Modified: HTTP-date Following request: If-Modified-Since: HTTP-date

Last-Modified: HTTP-date Following request: If-Modified-Since: HTTP-date Response: Entity modified: HTTP 200 OK Not modified: HTTP 304 Not Modified

Last-Modified: HTTP-date Saves bandwidth!

ETag: quoted-string Following request: If-None-Match: quoted-string

ETag: quoted-string Following request: If-None-Match: quoted-string Response: No match : HTTP 200 OK A match: HTTP 304 Not Modified

Saves bandwidth, too! ETag: quoted-string

If-Modified-Since If-Unmodified-Since If-None-Match If-Match

ETag × Last-Modified hash (GUID) × HTTP-date (seconds)

ETag × Last-Modified hash (GUID) × HTTP-date (seconds) weak+strong validation × strong

ETag × Last-Modified hash (GUID) × HTTP-date (seconds) weak+strong validation × strong needs content × needs date

Request+Response header Cache-Control: whatever

Request+Response header whatever = max-age , no-cache , public , must-revalidate (response only), ... Cache-Control: whatever

Pragma: no-cache Request+Response header

Pragma: no-cache Request+Response header Request: HTTP 1.0 variant of Cache-Control: no-cache

Pragma: no-cache Request+Response header Request: HTTP 1.0 variant of Cache-Control: no-cache Response: meaning undefined, wtf

Proxy cache CLIENT (BROWSER) WEB SERVER

Application level caching

Configuration Does not change often

Configuration Does not change often Parse (files)/read (from db) and store to APC

APC: The Alternative PHP Cache PHP extension Data store (also opcode cache)

APC: The Alternative PHP Cache Data persist between requests

APC: The Alternative PHP Cache Data persist between requests … until deleted or cache cleared or server restarted

Database connection cache Persistent connections (don't work) Connection pooler

Database query cache Some systems have query cache

Database query cache Some systems have query cache Some don't

Result set cache Some data don't change

Result set cache Some data don't change Fetch and store to memcached

Memcached Client-server architecture Key-value in memory store for strings and objects

Problems with caching

Data change sometimes but not often enough Employee list of a company

Data change sometimes but not often enough Employee list of a company Invalidate cache when adding or removing employees

Data change sometimes and delay is okay Translations from database

Data change sometimes and delay is okay Translations from database Introduce cache lifetime

Moar cache keys for the same data Sorted employee list (asc, desc)

Moar cache keys for the same data Sorted employee list (asc, desc) Cache groups

Cache groups Keys: list-sorted-asc, list-sorted-desc

Cache groups Keys: list-sorted-asc, list-sorted-desc Group „list“: list-sorted-asc, list-sorted-desc, list-unsorted

Cache groups Keys: list-sorted-asc, list-sorted-desc Group „list“: list-sorted-asc, list-sorted-desc, list-unsorted Delete group „list“ when adding/removing

Cache wherever and whatever

… but delete your whatever when needed

Caching is magic

Caching is magic but not automagic

Caching is magic but not automagic until now

Thanks for listening Michal Špaček, @spazef0rze BTW, love caching? skypecareers.com!

http://webexpo.cz	323
http://webexpo.cz	323
http://webexpo.net	28
http://www.michalspacek.cz	10
http://www.linkedin.com	7
http://twitter.com	3
http://test.webexpo.cz	3
http://us-w1.rockmelt.com	3
http://webexpo.innit.cz	2
http://webexpo.innit.cz	2
https://twitter.com	2
http://paper.li	2

Caching Strategies

by Michal Špaček

Accessibility

Categories

Upload Details

Usage Rights

12 Embeds 708

Statistics

Caching Strategies Presentation Transcript