| Skia Task Scheduler |
| =================== |
| |
| This directory contains code for a custom Swarming task scheduler used by Skia's |
| bots. |
| |
| ### Motivation ### |
| Skia's automated testing involves sets of tasks which depend on one another, |
| for example compiling code and then running tests on a particular platform. |
| These tasks are performed on Skia's bots via Swarming. We need a way to |
| intelligently schedule these Swarming tasks to optimally utilize the machines |
| in our test lab. In particular, we want to keep up with incoming commits to the |
| Skia repo by testing multiple commits as part of a single task, and then during |
| idle time run tests at commits which were previously batched to increase the |
| granularity of our test data. Additionally, the scheduler must keep track of the |
| directed acyclic graph of tasks for each commit. |
| |
| ## Design ## |
| At a high level, the scheduler first generates a set of all tasks which could |
| possibly be scheduled, filters out tasks which cannot run (eg. due to |
| unsatisfied dependencies) or should not run (eg. we've already run it), then |
| assigns a score for each candidate task based on the value added by running that |
| task (eg. how many new commits it tests, or how large a batch it bisects). It |
| then sorts the tasks by score to form a queue. When a swarming bot is free, the |
| scheduler triggers the highest-scoring task candidate which matches the |
| Swarming dimensions of the bot. Detailed design can be found here: |
| https://docs.google.com/document/d/12DzzmeDBDomNxTWWtHCRIfj6MoB8Yvw4v5horGuJPek/edit |
| and here: |
| https://docs.google.com/document/d/1tKlBi0reIKo6ActxN8TQY-4t80uQCJXv_CW9WVWG5w8/edit |
