facebookresearch/hydra

Consider supporting newer Ax features in Ax Sweeper

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#3177 opened on May 15, 2026

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Description

Follow-up to #3176.

Ax Sweeper is being updated from the old Ax 0.1.x-era dependency to the current Ax API. Current Ax exposes several capabilities that Hydra Ax Sweeper plugin does not currently model. Some of these may be useful to Hydra users, but supporting them would expand the plugin public configuration surface, so we should first collect concrete use cases.

Potential features to consider:

  • Multi-objective and scalarized objectives.
  • Stepped range parameters via Ax step_size.
  • Hierarchical or conditional parameters.
  • Derived parameters.
  • Experiment persistence/resume via JSON or SQL storage.
  • Generation strategy configuration knobs.
  • Tracking metrics or Ax-native trial-level early stopping.

Community feedback requested:

  • Which of these would you actually use with Hydra Ax Sweeper?
  • What is the concrete use case?
  • What Hydra config shape would feel natural?
  • Are there backward-compatibility concerns with existing sweeps?

This issue is for collecting interest and shaping the direction. If there is clear demand, we can split individual features into separate focused issues or PRs.

Timeout: if there is no substantive community interest by May 16, 2027, maintainers should close this issue as not planned.

Contributor guide

Tech stack
python
Domain
backendtooling
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
needs investigation
Prerequisites
Familiarity with Hydra Ax Sweeper pluginBasic knowledge of Ax optimization library
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
This issue is a follow up to #3176 and seeks community feedback on incorporating newer Ax features (e.g., multi objective optimization, stepped range parameters) into the Hydra Ax Sweeper plugin. To contribute, review the Ax documentation for the listed capabilities and comment on which features you would use, along with concrete use cases and desired Hydra config shapes. Since there are no assignees or linked PRs, this is purely a discussion issue; maintainers will consider splitting into separate issues if there is enough interest.