Why AO3 Was Down

https://www.reddit.com/r/AO3/s/67nQid89MW

by danso • 1 year ago

156 83 1 year ago

reddit.com

schoen• 1 year ago

A bookmark for every view of "Gangnam Style"!

https://arstechnica.com/information-technology/2014/12/gangn...

wging• 1 year ago

That article was from 2014, it has many more views now (about 5.6 billion).

notorandit• 1 year ago

typical database column

Typical for 70s and 80s.

Honestly, designing a 21st century database is a different thing if compared to back then.

You can use 128 bit integers, provided that you really want to use integers. And maybe you put a timestamp along.

j16sdiz• 1 year ago

let's use 128bit integer and handle them like floats in php!

and maybe put a 32bit timestamp along and pretend it can somehow store more than a 32bit integer can.

jarofgreen• 1 year ago

or use UUID/GUIDS, many databases (eg PostgreSQL) and frameworks (eg Django) support them.

dwedge• 1 year ago

Using uuids can cause lots of problems with indexing, fragmentation, row size and index size

throwawaysoxjje• 1 year ago

Nah I made the same mistake back in 2009 for a system that was storing behavior events during malware analysis.

You don’t often expect to have two billion of something until you do.

9dev• 1 year ago

It's not like those two billion things just materialise in your database, right? Someone must have watched that graph climb, and climb, and climb, approaching the limit.

shakna2• 1 year ago

Salesforce is a rather popular platform.

Its defaults are also either a 18-character ID, or a 32bit integer. So, unless you take the effort to actually fight Apex, you're gonna hit this problem sooner or later.

quickthrowman• 1 year ago

Doesn’t an 18-character alphanumeric ID give you 18^36 combinations? 1.54 x 10^45 seems like enough combinations.

Sharlin3• 1 year ago

One of the first things I internalized about databases was "just always use BIGSERIAL for primary keys". There are very few good reasons not to.

looperhacks• 1 year ago

Maybe don't: https://wiki.postgresql.org/wiki/Don't_Do_This#Don.27t_use_s...

rsynnott5• 1 year ago

The website appears to date from 2008. This was a _very_ common latent bug at that point, particularly because Rails would basically force you to implement it. I assume this got fixed at some point, but for a long time all ActiveRecord models had an autoincrementing ID, which had to be a signed 32 bit int. There were scary monkey-patching workarounds if you wanted something more sensible.

EDIT: And, yes, it is apparently Rails! https://fanlore.org/wiki/Archive_of_Our_Own#Timeline

RainyDayTmrw2• 1 year ago

It's kinda impressive that they got to 2 billion rows - with indexes, no less - without falling over.

jiggawatts2• 1 year ago

Point queries — typical of this kind of app - scales as log(n) in the number of rows. (Assuming a typical b-tree database index.)

This kind of workload cheerfully “scales” to your disk capacity.

RainyDayTmrw2• 1 year ago

Locking would make that more complex, I believe?

charcircuit• 1 year ago

to fix it they have to migrate the entire database to use a different type for bookmark IDs... except of course this will take a while because there are two Billion Of Them Lol

You can shard them between 2 tables. Then migrate them to a single one later.

ohdeargodno3• 1 year ago

There's no SLA for Harry Styles porn. Run the migration, lock the table for two days and redo the same in 13 years when you get to 4 billion bookmarks.

kijin• 1 year ago

In 13 years, the Unix timestamp will probably be a much bigger problem.

camel-cdr3• 1 year ago

There's no SLA for Harry Styles porn

But what about my good night's sleep? How can I go to bed without reading about my favorite blorbos?

rsynnott5• 1 year ago

I mean I’d assume they went for a 64bit integer. In a few million years, people who are into weird porn about whatever the temporally local equivalent of Harry Styles is (probably some sort of robot) will once again be mildly inconvenienced.

madaxe_again2• 1 year ago

This is like seeing a brick wall 40 miles down a straight road and yet still managing to drive into it, and then blaming the wall.

darkwater2• 1 year ago

I guess that whoever maintains that infra simply hadn't thought of it or was not aware. It's not something you get for free in a monitoring system with some agent like disk usage for example. You need to know and remember you have a hard limit on IDs and be aware at which ID you are.

hinkley• 1 year ago

Meanwhile if I keep reminding people where the wall is and how fast we are approaching it I’m considered “negative”. That”s the real reason this stuff happens. If someone noticed, the got tired of harping on it and without the constant barrage everyone else immediately let it go out of sight, out of mind.

ohdeargodno3• 1 year ago

Ao3 doesn't have a dude getting slack alerts by a dozen monitoring agents. It's one of the last holdouts of the old, more personal internet. Hell, it's even certain that they forgot or even didn't know that the type was an unsigned int.

And that's perfect. Blame the wall too, because it was running just fine. It's a site to write (mostly porn), with better uptime and more daily users than most of the companies posted on HN daily.

camel-cdr3• 1 year ago

I wasn't sure what the percentage of porn is, so I counted the number of works for each maturity rating:

    4,247,583: Teen And Up Audiences
    4,173,082: General Audiences
    2,816,083: Explicit
    2,271,446: Mature
    1,676,061: Not Rated

alt187• 1 year ago

This is like seeing a brick wall 40 miles down a straight road and yet still managing to drive into it, and then blaming the wall.

Not really, no. For example, if you drive into the wall, you may die.

Another experience that feels like death is working in a company that implements on-call rotations.

It would be too easy to draw out a parallel between how you approach a free fanfiction website (the website should mystically owe you five 9's uptime) and the mentality that metastased in the industry.

Instead, I'm gonna take this opportunity to point out that the AO3 downtime affected you, as a non-user, enough to vitrify the admin, where hardcore users laughed it off (because they're not entitled toddlers).

randallsquared• 1 year ago

enough to vitrify the admin

Not sure it was that solid.

madaxe_again2• 1 year ago

I don’t think I turned the admin into glass, nor vilified them - just pointed out that this sort of thing is readily avoided.

But sure, I committed a hate crime.

Groxx2• 1 year ago

Ha, a site I worked on hit this limit for the "follow relationships" table - had to build a new compound key table to migrate to, with triggers to dual read/write, to unbreak everything. In a few hours of "wtf" -> "oh crap" -> "well I guess we gotta do it right this time" and quick coding.

And then I pulled apart PT-OSC to make it more... less incredibly stupid about resource use, so it wouldn't cause too much load while it backfilled. And let it run for about 6 weeks.

Good luck! It's a fun problem to have - excess success, and a light puzzle to solve :)

bilka• 1 year ago

Do you happen to have those PT-OSC changes around? We've already migrated bookmarks with the downtime (with PT-OSC), but there are more tables that would be nice to get migrated away from int without going into maintenance or shedding a lot of load.

Groxx2• 1 year ago

No, it's long, long gone.

When I did it, the script was a bit of a mess of trigger setup, and then a backfill that only monitored replica lag, as if the status of the much less heavily used failover instance was somehow the most important part of a database. Hopefully that's no longer true, and none of this is necessary any more.

So I essentially split it in half, so I could keep only the trigger setup, and carefully read the queries the backfill would perform so I could duplicate it. And then wrote a very simple loop of "select N records, copy to new table, check how long that took. scale up by min(5%, 100), scale down by 30%, if outside target bounds".

Intentionally very polite to the main DB, because once the triggers are in place it really doesn't matter how long it takes. It dropped down to single digits at peak load on some days, so I think that was the correct choice.

12_throw_away• 1 year ago

For anyone who feels like looking up exactly what this bookmark was pointing to: I did, and very much wish I hadn't!

eknkc• 1 year ago

What in the name of fuck

heavensteeth• 1 year ago

I ask in complete earnest: is that your honest reaction to seeing it, or did you hype it up for your comment? Personally very little could evoke that kind of reaction from me. Maybe a little, "oh, that's an interesting thing to be turned on by" but for the most part, who cares?

MangoToupe2• 1 year ago

New to the internet?

ahazred8ta3• 1 year ago

You remember the Supernatural line "Together? Don't they know we're brothers??" "They don't care." This was the site. Sweet cheese and crackers. <https://archiveofourown.org/tags/Dean%20Winchester*s*Sam%20W...>

nikanj2• 1 year ago

I know I'll regret this, but how do you navigate to bookmark by column id?

camel-cdr3• 1 year ago

The link is in the reddit comments.

It's Dead Dove though.

zerocrates• 1 year ago

Is it faster to convert a column like this to unsigned? Obviously assuming you don't use negative IDs in the application.

That's much more of a "kick the can down the road" solution to only double your usable range, but if all positive the values in the rows shouldn't actually have to change, just the column metadata, so it could theoretically be more or less instantaneous. I guess in practice this doesn't happen; the server would rather use its generic "rebuild the table" alter method for changing a column type.

But it seems like you could reasonably do it if it's a signed-to-unsigned change and there's no negative values and there's an index on the column to make checking that fact fast. Or one of those third-party/lower-level type tools could let you do it without any checking.

adamcharnock• 1 year ago

An interesting idea! I suspect a major speed up would come from the fact that the column is staying the same size. So (I assume) far fewer bytes would need to be moved around.

afandian2• 1 year ago

I don't know what DB was used in this csae, but Postgres doesn't have unsigned integers. It always struck me as hugely wasteful, as e.g. sequences start at zero by default.

masklinn• 1 year ago

At $dayjob we've actually used this property once or twice: if you need to merge two tables you can keep the positive ids for the first one, and use negative ids for the second one. It only works once, but damn if it's not effective when you need it, and it conveniently flags all the records with an id under some limit (positive and negative both) as "pre-transition" record when you're looking for patterns.

kristianp2• 1 year ago

It's mysql.

p0w3n3d• 1 year ago

Hacker News helps me everyday break my information bubble. Archive Of Our Own is something that I wouldn't walk into when wandering through the internet

chii• 1 year ago

I wouldn't walk into when wandering through the internet

it's interesting that some people are on the internet but is very well insulated! AO3 is very well known for me...

parlortricks• 1 year ago

this is the first i've heard of it

diggan3• 1 year ago

it's interesting that some people are on the internet but is very well insulated

Not sure I'd call it "insulated", the internet is just very, very vast, even when considering "just" the English-speaking web. Then you have all the other "versions" out there too that are kind of hidden to most people :)

Anecdotal, but also first time I heard about AO3, and I'd consider myself having broad interests and generally well-read, although my interests doesn't include fanfiction so maybe not so weird I haven't heard about it before.

Sharlin3• 1 year ago

I’d say AO3 is the insulated part.

Having been an active internet user for longer than most AO3 users have been alive, the first time I heard about it was a few years ago in a student radio show about the fanfic genre and culture. Poorly written smut featuring popular culture characters has just never been my thing. Probably because I’m not that much of a fan of any specific fictional setting or franchise in the first place.

paganel• 1 year ago

First time I read about it, not exactly sure what it is, by quickly glancing at it. Looks like a collection of links to some fan-fiction stuff.

bananaflag• 1 year ago

It is currently pretty much the main repository of fanfiction.

I've been reading fanfiction on the Internet for two decades, so for me it would've been quite hard to miss it.

MangoToupe2• 1 year ago

Archive Of Our Own is something that I wouldn't walk into when wandering through the inter

Kind of crazy to hear. AO3 is so culturally massive I don't know how you miss it.

malnourish• 1 year ago

I have never heard of it, and I've been pretty active on the Internet since the early 2000s.

rsynnott5• 1 year ago

The internet’s big. I’m aware of it due to a moderate tvtropes addiction (there’s a enough crossover that it’s hard to miss) but probably otherwise wouldn’t be familiar.

ahazred8ta3• 1 year ago

Remember "Don't they know we're brothers??" from Supernatural? This was the site. <https://archiveofourown.org/tags/Dean%20Winchester*s*Sam%20W...>

XKCD on index number exhaution: https://xkcd.com/865/ Remember Data and the Borg? "Accessing... accessing... accessing... accessing..."

olivermuty• 1 year ago

Uh, the bookmark that broke it all was to a part of the internet I have yet to experience since getting online some 30 years ago. Alphas and betas and omegas, it was a wild ride.

Freak_NL3• 1 year ago

The bookmark itself, for the curious:

https://archiveofourown.org/bookmarks/2147483647

That alpha/beta/omega thing is quite huge apparently, but not something you would ever encounter outside of specific subcultures (like Archive of Our Own):

https://en.wikipedia.org/wiki/Omegaverse

CubsFan1060• 1 year ago

I didn't see it mentioned, but the quick fix for this (assuming you don't depend on the order of id's) is just to alter your sequence to use the max negative int, and increment from there. Not a complete solution, but buys enough time to actually fix the issue.

kristianp2• 1 year ago

They're using mysql and Rails. And Jira.

Mysql2::Error: Out of range value for column 'id' at row 1 (Mysql2::Error)

https://otwarchive.atlassian.net/jira/software/c/projects/AO...

Why AO3 Was Down

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