[x5315]

This was a bug. We rectified it as soon as the issue was brought to our attention.

The original version of this product launched in March 2013. Its intention was to just "bump" brands in your follow lists to the top, not to start placing Promoted Accounts randomly in the list—what the headline suggests. That was the bug.

[jacquesm]

Your account appears to be 100% anonymous and does not have any clear link with twitter that implies that you are really speaking for the company. Unlike say Matt Cutts saying something about Google handling spam.

I'm a bit skeptical about 'bugs' like this lasting for over a year and a half without there being some kind of intent involved. It's hard to imagine how this bug could have come into existence in the first place, harder still to imagine that code review and testing didn't catch it and that nobody complained about it in the meantime.

Random accounts appearing in followed/follower lists would be weird enough given that that is core twitter functionality but to have that happen specifically to promoted accounts would appear to be by design rather than by accident, especially if those promoted accounts did not appear in the lists to begin with. That would require some serious overriding and additional logic unless twitter is implemented in an unlogical way.

To put it plain: a change in sort order does not normally change the contents of the lists, that requires a lot more work and is usually not unintentional.

[x5315]

Sorry, this is me: http://twitter.com/x5315. I'll update my bio, how's that?

The 'bug' didn't last for over a year and a half. The product has existed for that long.

The bug was in the advertiser selection process. There was an issue with the job/dataset we use to select which advertisers to choose. It should only have been people in the follow lists.

As for "a change in sort order does not normally change the contents of the lists". Due to the size of some of the lists, we don't load the entire list when we show you the first 20 or so. Therefore, we would require an insertion process.

[pc86]

Thank you for clarifying this. I'm obviously not familiar with Twitter's code to any extent, but it seems reasonable you'd need the insertion process regardless.

Out of curiosity, can you speak to how long this bug actually appear in the wild before it was corrected?

[nemothekid]

This post perturbs me a bit - aside from the hardcore skepticism - I don't see how anyone who doesn't work for Twitter would be able to comment on the implementation of Twitter's follower lists.

It's strange because to me you are suggesting that I shouldn't believe an engineer at Twitter that it was a bug, because the bug should be impossible based on an imaginary implementation from someone who doesn't work at Twitter in order to prove that Twitter is 100% malicious.

I'm beginning to wonder is most posts like this play at our biases (we want to believe that Twitter is making some underhanded deals with "evil" advertisers), rather than taking a more neutral view.

[click170]

Thank you for clarifying.

It doesn't reflect very well on the company though when a bug like this is seen as something that people believe you would actually attempt to implement - even if this was a mistake. What does that say about what people think about that company?

[x5315]

I agree. I tend to think of it like this: https://twitter.com/attaboy/status/550003457982087169

[davidgerard]

Yes ... but why would people assume a deliberate decision rather than a bug? That was the question you were just asked.

[vlad]

When did this bug appear? I believe I noticed this issue when logging in with Twitter weeks ago.

[x5315]

I, personally, don't know. We'll have some kind of post-mortem internally to work out what happened, and how to make sure it doesn't happen again.

[snsr]

I'd like to read more about this - do you have a link to any related discussions or posts?

[x5315]

I don't know what comms has said publicly and where, but this is a description: https://news.ycombinator.com/item?id=8823792