1638316 - Add a toggle to show replaced tasks

Status: NEW

(Tree Management :: Treeherder: Frontend, enhancement)

Description

[Andrew Halberstadt [:ahal]]

Please move to appropriate component.

In the taskgraph, there is a concept of "optimziation by replacement". This means that a task that ran on some previous push (not necessarily on the same branch), satisfies the requirements of the current task. So rather than run the current task again, we "replace" it with the older task.

This is useful for things like toolchains. We run the clang toolchain once, then all subsequent builds use the artifacts from that same task until it expires or until we make a change to it and it needs to re-run.

In bug 1636271 we are considering optimizing by replacement all test tasks on mozilla-central that previously ran on autoland with the same revision. This means it will be difficult for sheriffs to get a full picture of the tasks on mozilla-central.

If there were a button on treeherder that let you "fill in" replaced tasks (think something like the Add New Jobs UI), then this wouldn't be a problem. The data for replaced tasks is already available in the labels-to-taskid.json artifact on the Decision task. This artifact contains both the tasks that ran on the push, and the tasks that ran somewhere else.

So treeherder could presumably download it, then for each label, taskid pair, fill in a symbol for taskid if the label doesn't already exist on the current push.

I wouldn't say this blocks bug 1636271, but it's related.

Comment 1

[Sarah Clements [:sclements]]

I think this could all be done in the UI, since we're now fetching artifacts directly from taskcluster.