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Reddit crashed because of the growing subreddit blackout

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Re: Reddit crashed because of the growing subreddit blackout

#2
I have not read a reddit devblog or anything like that. My guess is they are doing some kind of caching of posts via elasticsearch/redis or something similar. It must depend on the privacy settings of a sub.

So when 1000 subs go private, they potentially had to update hundreds of millions of comments.

Anyone else have a theory?

Re: Reddit crashed because of the growing subreddit blackout

#4

I have not read a reddit devblog or anything like that. My guess is they are doing some kind of caching of posts via elasticsearch/redis or something similar. It must depend on the privacy settings of a sub. So when 1000 subs go private, they potentially had to update hundreds of millions of comments. Anyone else have a theory?

The subreddits that are most popular are on high performance servers while the subreddits that are less popular are on lower performance servers?

Re: Reddit crashed because of the growing subreddit blackout

#5

I have not read a reddit devblog or anything like that. My guess is they are doing some kind of caching of posts via elasticsearch/redis or something similar. It must depend on the privacy settings of a sub. So when 1000 subs go private, they potentially had to update hundreds of millions of comments. Anyone else have a theory?

Cache invalidation makes sense.

Could also be some kind of fanout query that assumes the top subreddits are open and wastes CPU cycles.

Re: Reddit crashed because of the growing subreddit blackout

#6

I have not read a reddit devblog or anything like that. My guess is they are doing some kind of caching of posts via elasticsearch/redis or something similar. It must depend on the privacy settings of a sub. So when 1000 subs go private, they potentially had to update hundreds of millions of comments. Anyone else have a theory?

I'm skeptical. Most of the outages I've been involved in have been for way dumber reasons than that. Based on my dumb experience, my guess is that the handling for a user trying to access a private subreddit stressed some system that doesn't make sense to even exist.
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