LiveJournal's Backend and memcached: Past, Present, and Future

Blogging before blogging was a word, LiveJournal.com started off as a hobby project for Fitzpatrick and some friends and is now home to well over 4,000,000 accounts, over half of which are in active use.

With a built-in social networking system, per-journal-entry security, message boards, a LJ/RSS/Atom news aggregator, support for 20+ languages, a technical support system, and more, LiveJournal.com is a beast of an open source project, addictive to both users and developers. What's just as interesting, however, is how it all runs.

Come learn about LiveJournal.com's backend, past, present, and future. Discussion will include:

• The site's history: how it's gone from one server to over sixty, adapting both its code and architecture to fit each other as the site grows.

• Load balancing: commercial vs. open source vs. home-grown open source. When to use each, and how to use them effectively together.

• MySQL tricks and replication: when and how to use MyISAM, when to use InnoDB, partitioning your data across clusters, moving users around clusters, replication topologies, for high-availability and easy maintenance, the DBI::Role library for load balancing and role-based handle acquisition.

• Memcached, the site's distributed caching daemon and client libraries, originally built for LiveJournal, but in the last year now in use by Slashdot, Wikipedia, and others. Learn how memcached was used to make things really fast and avoid hitting the database. Learn why memcached works so well with lots of machines compared to local caching, and what been done to make the protocol, server, and memory allocator so fast.

And, of course, audience questions and comments will round out this session.