What’s happening?

1. Every Twitter post has an ID number that goes up by 1 each time.
2. When a computer program stores a number, it sets aside a certain amount of space for it. Bigger numbers take more space because they have more digits.
3. One common format is called a “signed integer.” It has 32 binary digits (1 or 0 only) with one digit set aside to indicate a minus sign. The biggest number it can store is 2,147,483,647.
4. Twitter’s status IDs are approaching that number.

So what’s the likely impact?

• Twitter itself can handle bigger numbers and will be fine.
• Third-party apps that store the ID in a bigger format will be fine.
• Third-party apps that store the ID as text instead of a number will be fine.
• Third-party apps that store the ID in this particular format will end up with bad IDs as they try to cram a big number into a small space.

If I were to guess, the most likely breakage would be that replies might be attached to the wrong previous post — but again, only with apps that use this particular format for numbers.

Twitter itself will probably sail through cleanly (and has been planning to move up the schedule so that affected app developers don’t have to fix things in the middle of the night), so don’t expect any fail whales. Unless so many clients have problems that lots of people switch to the website.

Update: Not surprisingly, most Twitter clients are unaffected by the Twitpocalypse. I’ve used both Twidroid and Twhirl with no problems since Twitter passed the mark. I figured a few would get tripped up, but the real surprise is that it hit Twitterrific. One of the most popular clients on the iPhone? They do have an update, but a lot of people are unable to connect.