PSA: Improving trybot feedback with -k 3 and Max-Compile-Failures footer

[Will Yeager]

Hi chromium-dev,

Chromium trybots now default to compiling with the ninja flag -k 3 (keep going until 3 failures). It was previously unset, which is equivalent to -k 1.

Why the change? This update is in response to a feature request in crbug.com/442618066. The goal is to speed up the feedback loop by surfacing multiple build errors - especially those that may not be easily reproducible on your local machine - in a single tryjob run.

Why 3? We’re starting with 3 as a conservative default to provide enough signal to catch independent errors without overloading bot resources. We’ll be monitoring the impact and are happy to iterate based on the data.

Overriding the default. If you need to override this value for a specific CL (e.g., for large-scale refactors), you can use the new git footer: Max-Compile-Failures: N (where N >= 0 and 0 means infinity).

Example of default -k 3 behavior:

Example of Max-Compile-Failures footer:

On behalf of Chrome Operations,

Will