Edit 23:54: Added second-to-last paragraph, yay.
Edit 00:06: Few minor edits suggested by whitaker.
Edit 00:25: Reworded the last paragraph thanks to whitaker. Go whitaker!
Okay, answered the call of teh abe and came up with this. Feedback please?
- FAQ title: What is the "express lane"? What benefit does it offer?
Even with more than two million active members, it can sometimes be hard to imagine that a web site such as LiveJournal.com serves up tens of millions of dynamically-generated pages each day, let alone that it is capable of doing this. The way in which LiveJournal does this relies partly on a technique called "load balancing", where your request is sent to one of dozens of different web servers depending on which server is the least busy at the time.
During times of heavy site load, LiveJournal's web servers frequently become too busy to accept new requests, and this creates a queue of requests on the load balancers. New requests are added to the back of the queue, and requests at the front of the queue are passed to the next available web server.
One of the benefits afforded to paid accounts (http://www.livejournal.com/support/faqbrowse.bml?faqid=21) is a place on the "express lane". This means that when logged into a paid account, requests for LiveJournal pages are automatically added to a secondary queue at the front of the main queue. As a result, those requests in the secondary queue are passed to web servers faster, effectively giving paid accounts priority access to the site.
As a convenience, paid accounts are afforded the ability to see, on each page loaded, how much time was saved as a result of the express lane. To do this, view the HTML source code of the LiveJournal page you just accessed; if you are unsure of how to do this, consult your browser's documentation. Near the top of the source code, you will see a comment indicating how much time was saved, like this:
<!-- LiveJournal ExpressLane: You received this page before 1234 free users, saving approximately 3 seconds! -->
LiveJournal's main priority as a service is to offer all users, free and paid alike, fast and uninterrupted access to the site at all times. The web servers used to process these millions of requests are fast and numerous enough to ensure that this goal is maintained as much as possible; however, like any service, LiveJournal will encounter unavoidable periods of heavy site load. The aim of the express lane is simply to reduce the negative effect these peak times have on our paid users.