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Comment by UnoriginalGuy | Hacker News Reader

> They (apparently) didn't had code reviews

I don't get that. There was no code issue. The old and new code both worked as intended, it was a deployment and deployment-verification problem.

> They didn't had a staging environment

Yes they did. They staged the new code and tested it. They did a slow deployment also.

> They didn't had a contingency plan to revert the deploy

They did revert the deploy within the 45 minutes. It made it worse.

I think you need to re-read the article. Your assessment is strange given the event.

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> I don't get that. There was no code issue. The old and new code both worked as intended, it was a deployment and deployment-verification problem.

A code review could raise the issue of repurposing a flag in case they had to revert the deploy. Changing the semantics of a flag is a big no-no anyway, and there are ways to guard against that.

> Yes they did. They staged the new code and tested it. They did a slow deployment also.

But they didn't had a staging environment that matched their live environment, apparently. You want a staging environment that is 1:1.

> They did revert the deploy within the 45 minutes. It made it worse.

If you think reverting a deploy by simply pushing an older version is the same as a contingency plan, think again.

Code review could have been another set of eyes to predict the problem of reusing a flag.

If the message was as compact and low level as possible it was probably a bit flag, so in that context it makes sense to repurpose it.

Being so removed from binary and bit level interactions it can be easy to forget things like this.

I agree with the GP; I don't think code reviews or testing was the problem.

I think the best-practices they violated is that they deprecated and repurposed a flag within a single release cycle. That sort of activity should take two release cycles at least, one to remove the old functionality and one to add the new functionality.

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