| Skia Build Scheduler |
| ==================== |
| |
| This directory contains code for a custom buildbot scheduler used by Skia's |
| buildbots. |
| |
| ### Motivation ### |
| The built-in buildbot schedulers trigger builds at each commit in the repo. |
| In most cases, if the bots lag behind a little, multiple commits are batched |
| into a single build. This is good for preventing the bots from falling behind |
| during the day, but the result is that the blamelists for performance and |
| correctness results potentially include a lot of commits, which makes |
| regressions difficult to track down. |
| |
| Additionally, the bots have large swaths of idle time during the night and on |
| weekends, and are occasionally idle during the day. They could be using this |
| time to run additional builds which separate the commits which were batched |
| together in previous builds. |
| |
| ## Design ## |
| This build scheduler takes a different approach. It considers the commits |
| within a time period and generates scores for commit/buildbot pairs (aka |
| "build candidates") which represent how much value would be obtained by running |
| a build on each buildbot at each commit. The build candidates are stored in a |
| sort of priority queue, sorted by their score. |
| |
| Whenever a given builder is idle, the scheduler takes the highest-scoring build |
| candidate for that builder from the queue and schedules it using the |
| BuildBucket API. |
