The Twitpocalypse is upon us and sooner than previously expected. The name is given to a bug, very similar to the well-known Y2K, initially expected to hit Twitter sometime today. But the Twitter team moved up the Twitpocalypse to 21:00 GMT on June 12 so they could better handle it in a more controlled environment.

The bug is based on the fact that every tweet has a unique identifier associated with it. The number of tweets, along with the identifier, is about to reach 2,147,483,647 which is in fact the highest number that can be represented by a 32-bit signed integer. At this point third-party clients for the service would send tweets with negative IDs and display other strange behavior.

“The overflow of the 32-bit signed integer value for status ids (a.k.a “The Twitpocalypse” [1]) is fast approaching. The current estimate is around tomorrow at around 11am GMT, or 3:00am Pacific time in the case of Twitter. There is some discussion internally about accelerating things so we’ll be in the office and able to cope. Nobody is their freshest at 3:00am, not to mention it would be nice to not have apps broken throughout the weekend if one-person developer teams don’t notice,” Twitter engineer Matt Sanford said in a Google Group thread.

“The responses to @twitterapi and all discussions internally show a preference to not waiting until the middle of the night. The current plan is to force this issue at 21:00 GMT (2:00pm Pacific/5:00pm Eastern for those in the US). This will let us make sure we have all staff available in the unlikely event something goes wrong on our end,” he later added.

Twitter's main page was not expected to be affected and in fact it has not been. Some third-party clients however were hit but it was mainly on a small scale. Twitterific 2.0.1, a Twitter client for the iPhone, has had problems although the Mac version was not affected. Apps hit by the bug are Destroy Twitter, TweetDeck and possibly others. Most developers have said the problem will be fixed during the weekend.