Evan 9e9c608053 perf: cut core-sim GC churn another 36% (61% cumulative) (#4496)
## Summary

Round 2 of GC-churn reduction, attacking the next tier of allocation
sources found by the profiling harness from #4494. All changes are
**behavior-preserving** — the simulation is bit-identical (final hash
unchanged on three seeded runs).

### Changes

| Site | Change | Churn target |
|---|---|---|
| `Player.units()` / `Game.units()` | Rest parameter → fixed-arity +
array overloads (`units()`, `units(types[])`, `units(t1, t2?, t3?)`).
The rest array was allocated on **every call** of one of the hottest
functions in the sim. Spread call sites (`units(...Structures.types)`)
now pass the array directly. `GameImpl.units()` builds one flat array
instead of `Array.from().flatMap()` per-player intermediates. | ~18 GB |
| `PlayerExecution` cluster flood fill | Results are plain `TileRef[]`
in mark order instead of `Set<TileRef>` — the generation-stamped visited
array already deduplicates, and consumers only iterate/measure. DFS
stack reused across fills. | ~3.7 GB |
| `SpatialQuery.bfsNearest` | Fused generation-stamped BFS with per-game
scratch buffers (`WeakMap`-keyed, same pattern as `PlayerExecution`)
instead of materializing a `Set` of the entire search area per query.
Identical traversal and tie-breaking. | ~2.2 GB |
| `NationWarshipBehavior` ship tracking | Single-pass loops instead of
`filter().forEach()`; dropped defensive `Array.from(set)` copies
(deleting the current entry while iterating a `Set` is well-defined). |
~1.4 GB |

### Results (Giant World Map, 400 bots, 12,000 ticks ≈ 20 game-min, seed
`perf-default`)

| Metric | Before | After | vs. pre-#4494 |
|---|---|---|---|
| Sampled allocations (incl. collected) | 59.2 GB | **37.8 GB (−36%)** |
97.7 GB (**−61%**) |
| GC count / total pause | 1,076 / 1,830 ms | 772 / 1,442 ms | 1,682 /
3,313 ms |
| Ticks/sec | 73 | **82** | 66 (+24%) |
| Mean / p99 tick | 13.6 / 39.2 ms | 12.2 / 36.0 ms | 15.2 / 49.9 ms |

`units()` no longer appears in the top-30 allocator list at all. The
remaining leaders (possible round 3): the minimap pathfinding `Cell`
pipeline (~8.5 GB), `diffPlayerUpdate`/`toFullUpdate` per-tick
serialization (~4.6 GB), and iterator allocations (~3.3 GB).

## Determinism

Final game-state hash unchanged on all three reference runs:
- Giant World Map 12,000 ticks: `57830793797434300` ✓
- Giant World Map 2,000 ticks: `55125379638382860` ✓
- World 1,800 ticks: `32337437717390864` ✓

## Test plan

- [x] Full suite green (1,905 tests), including updated `units()`
semantics tests (array overload, snapshot isolation, insertion order)
- [x] Hash equality on 3 seeded headless runs (2 maps)
- [x] Before/after 20-min GC benchmarks on the same commit base

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
2026-07-03 13:02:36 -07:00
2026-07-01 14:12:37 -07:00
2026-07-02 15:13:26 -07:00

OpenFrontIO Logo

OpenFront.io is an online real-time strategy game focused on territorial control and alliance building. Players compete to expand their territory, build structures, and form strategic alliances in various maps based on real-world geography.

This is a fork/rewrite of WarFront.io. Credit to https://github.com/WarFrontIO.

CI Crowdin CLA assistant License: AGPL v3 Assets: CC BY-SA 4.0

License

OpenFront source code is licensed under the GNU Affero General Public License v3.0

Current copyright notices appear in:

  • Footer: "© OpenFront and Contributors"
  • Loading screen: "© OpenFront and Contributors"

Modified versions must preserve these notices in reasonably visible locations.

See the LICENSE for complete requirements.

For asset licensing, see LICENSE-ASSETS.
For license history, see LICENSING.md.

🌟 Features

  • Real-time Strategy Gameplay: Expand your territory and engage in strategic battles
  • Alliance System: Form alliances with other players for mutual defense
  • Multiple Maps: Play across various geographical regions including Europe, Asia, Africa, and more
  • Resource Management: Balance your expansion with defensive capabilities
  • Cross-platform: Play in any modern web browser

📋 Prerequisites

  • npm (v10.9.2 or higher)
  • A modern web browser (Chrome, Firefox, Edge, etc.)

🚀 Installation

  1. Clone the repository

    git clone https://github.com/openfrontio/OpenFrontIO.git
    cd OpenFrontIO
    
  2. Install dependencies

    npm run inst
    

    Do NOT use npm install nor npm i but instead use our npm run inst. It runs the safer npm ci --ignore-scripts to install dependencies exactly according to the versions in package-lock.json and doesn't run scripts. This can prevent being hit by a supply chain attack.

🎮 Running the Game

Development Mode

Run both the client and server in development mode with live reloading:

npm run dev

This will:

  • Start the webpack dev server for the client
  • Launch the game server with development settings
  • Open the game in your default browser (to disable this behavior, set SKIP_BROWSER_OPEN=true in your environment)

Client Only

To run just the client with hot reloading:

npm run start:client

Server Only

To run just the server with development settings:

npm run start:server-dev

Connecting to staging or production backends

Sometimes it's useful to connect to production servers when replaying a game, testing user profiles, purchases, or login flow.

To replay a production game, make sure you're on the same commit that the game you want to replay was executed on, you can find the gitCommit value via https://api.openfront.io/game/[gameId]. Unfinished games cannot be replayed on localhost.

To connect to staging api servers:

npm run dev:staging

To connect to production api servers:

npm run dev:prod

🛠️ Development Tools

  • Format code:

    npm run format
    
  • Lint code:

    npm run lint
    
  • Lint and fix code:

    npm run lint:fix
    
  • Testing

    npm test
    

🏗️ Project Structure

  • /src/client - Frontend game client
  • /src/core - Deterministic game simulation
  • /src/server - Backend game server
  • /resources - Static assets (images, maps, etc.)

🤝 Contributing

Contributions and translations are welcome! See CONTRIBUTING.md for the workflow, the approved-issue process, project governance, and translation info.

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