Technology

I'm a backend developer and have to deal with this nonsense at my job. There are lots of options, each with tradeoffs, such as:

• rely on checking at the subreddit level - this means that every time you access a page, you need to check whether the subreddit is private, which means slower page loads
• include the flag on every post - flipping between private and public can be very expensive on the server
• embed some info in the URL - breaks links when switching back and forth and is also expensive, but you can cut down on some checks (e.g. no database hit for most checks; i.e. if it's private and you aren't logged in, you cannot access it)

And if you go for one of the two last options, you can reduce the hit when switching by being eventually consistent, meaning you don't change everything all at once but instead set the flag or change the URL in batches over a period of time. That takes effort to get right, and there's going to be inconsistency until everything is done.

So there are multiple ways to do it, and each way has a big chance at devs messing something up when they don't consider something like a bunch of subreddits going private all at once.

Or it could just be a run of the mill DDOS because some redditors wanted to troll Reddit.