swactor/CLAUDE/TASK.md
Developer ef87f7e1b9 feat: per-actor message budget for tick fairness
Research across ractor, tokio, Erlang/OTP BEAM, Linux CFS, and libuv
revealed that tick_all drained the entire mailbox per actor per tick,
allowing one hot actor to starve all others on the same worker.

- Add `actor_message_budget` to RuntimeConfig (default: 64 msgs/actor/tick)
- Modify tick_all to break after budget messages, yielding to next actor
- budget=0 restores unlimited (backward compatible) behavior
- 3 new fairness tests validating hot-cold actor scenarios
- New fairness benchmark group (cold_latency_under_pressure, throughput_by_budget)
- Fix RuntimeConfig struct literals across workspace crates

Inspired by BEAM's 4000-reduction budget and tokio's 128-op cooperative budget.
All 45 tests pass (42 original + 3 new).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
2026-02-12 11:11:30 +00:00

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Plan:
You are to improve this codebase via:
- investigating similar codebases
- identifying and summarizing their design decisions when compared to swactor:
- runtime engine
- benchmarking
- testing
- overall performance
- etc.
- implementing improvements based on your anaylsis
Workflow:
- Read `CLAUDE/TASK.md` and `CLAUDE/notes/progress.md`
- Identify what stage you are on.
- Read and update yourself as necessary.
- Proceed to accomplishing the next task as written in `progress.md`
- For each attempt at any step, keep a record. If you reach attempt 3, step back, document, and try something else.
- When done, because attempt limit or task success:
- update `progress.md` with:
- Completed this session
- Next steps (specific, actionable)
- Open Questions
- Blockers
- make a commit
- compress your context and start the loop again
Style:
- Do not add to existing modules in the root swactor `src/` they should stay as they are. You may modify but not change module structure.
- Integration tests in `tests/`, benchmark code in `benches/` (cap benchmark execution time at 2 minutes max). You may modify these as you wish.
- Report all your changes to architecture with changes to the `docs/` items
- all notes you wish to keep across iterations shall go in the `CLAUDE/notes/` folder
Example loop (not restrictive, feel free to ignore if prudent):
- Pick a related codebase and a concept to execute (benchmarks, test coverage, engine performance under various scenarios)
- compare to swactor
- make analysis
- implement plan
- execute
- evaluate
- repeat
Before git commit:
- all `cargo test` passes, including feature gated material
- if a test fails, investigate do not ignore or delete
- You can combine tests but not skip code paths or delete them for active code
- if a fix takes > 3 attempts, log and move on