If you follow twitter closely, you might have noticed the service disruption couple of times. Based on the recent Q&A post on twitter dev blog, it was mentioned that the reason of this downtime is below.

charles asks if there’s anything users can do to lighten our load. The events that hit our system the hardest are generally when “popular” users - that is, users with large numbers of followers and people they’re following - perform a number of actions in rapid succession. This usually results in a number of big queries that pile up in our database(s). Not running scripts to follow thousands of users at a time would be a help, but that’s behavior we have to limit on our side.

Twitter is built on Ruby on Rails framework, and it seems that they have problem scaling twitter to cater for huge queries and mass users. But the down shouldn’t be that long.

On my past job, I was quite familiar with above mentioned problem, when the database starts utilizing huge number of resources (memory and CPU) but processes nothing (database locking and blocking). But most of the time the issue is resolved in a short period of time.

Perhaps this is what twitter lacking of right now.

Michael is confused as to why we don’t have “an army of geniuses working day and night”. We’d love to, but it’s easier said than done. We interview constantly and have a talented recruiter bringing us exceptional candidates daily. We’re careful about who we hire, though, because we’re trying to build a great team in a sustainable way. We’re currently exploring supplementing our team with consultants, and we’ve accepted strategic help from outside organizations who actually do have armies of geniuses. If you’d like to lend your genius to our particular problems, have a look at our jobs page.

Techcruch has more detail about Twitter’s downtime.