Google's DoubleClick ad server went down today for about an hour, triggering a rare "P0" response from the company.

People who don't work in tech won't know what "P0" (or "P zero" or "p0") means, but within the software industry, P0 can be loosely defined as "the worst possible thing that can happen."

The ad server is back up and running now, but during its outage about one third of all web sites that carry advertising on planet earth were without ads. Some of them were unable to load their pages properly, and maybe $1 million was lost in ad revenue, collectively, as a result.

As Google's entire business is about serving ads in a completely reliable way, this was bad news.

We noticed that the DoubleClick glitch had been given the P0 label in this help forum for DoubleClick publishers. As dozens of anxious publishers poured into the bulletin board, wondering where their ads (and money) had gone, one client told the others:

We got this response: We're addressing as a "P0" extremely critical issue across DFP [DoubleClick For Publishers].  We don't have a timeline at this moment but I hope to have a timeline/resolution very soon.

This former Microsoft employee has a great description of how tech people think about P0 bugs:

P0     Do not do anything else, this is a blocker.
You can think of the Lancaster bomber flying over the English channel with 4 engines on fire … getting the fires out is a P0 priority.
P1     Must be fixed.
P2     Should be fixed, time and resource permitting.
P3     Might get fixed.
P4     Noted … this is one step away from the black hole.

Note that P0 isn't just a serious emergency, it's an emergency that is so severe no other work can take place until the bug is fixed. An existential threat, in other words.

A non-tech person might assume that P1 would be top priority. But this is the land of coders, and in coding, zero comes right before 1. Hence, P0.

See Also:

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