mirror of
https://github.com/bitsocialnet/5chan.git
synced 2026-08-03 07:41:04 +02:00
Tommaso Casaburi
1a33f7dc88
Playwright disables normal background throttling, so a hidden 5chan page keeps doing P2P and rendering work after a check finishes. Agents verifying in parallel across worktrees stacked whole browser engines on one machine. Add scripts/pw-session.sh, a wrapper that permits one active Playwright browser at a time and records who holds it: - The lock is machine-wide, not per-repository, because the contended resource is RAM and CPU. Every worktree and checkout shares one slot. - Acquisition is an atomic mkdir. Stale locks clear themselves: `open` reclaims any slot whose recorded browser is no longer `status: open` in `playwright-cli list --all`, so an interrupted workflow cannot strand the budget. When that list cannot be read the lock is left alone, so a broken CLI never silently disables the budget. - `open` exits 75 when the slot is busy; `--wait[=SECONDS]` blocks instead. - `close` always stops the browser, even when the lock was already lost, and never releases a slot held by a different session. - `status` reports the holder and whether its browser is still alive. Agent policy now runs browser engines and profiler batches sequentially, uses Chrome/Blink during iteration and the full engine matrix only for final verification, and never uses `close-all` or `kill-all` while other agents may own sessions. Covered by scripts/pw-session.test.js.
65 lines
3.1 KiB
Markdown
65 lines
3.1 KiB
Markdown
# Low-Spec Device Verification
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Use this playbook when you need to know whether loading, navigation, or interaction speed is a real user problem or just an artifact of a fast development machine. It adds CPU + network throttling on top of the normal `playwright-cli` verification flow.
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## When to run
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- A change touches navigation, data loading, list/feed rendering, images/media, or anything where "is this slow?" matters.
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- You cannot tell whether jank or lag is real because the dev machine is high-spec.
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- Before claiming a perf-sensitive change "feels fast".
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This is an extra pass, not a replacement for the standard Chrome/Firefox/WebKit verification.
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## How it works
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`playwright-cli` (`@playwright/cli`) has no throttle command, so throttling is applied through CDP via `run-code`. `scripts/pw-throttle.sh` wraps that call. The throttle is set on the page target and persists for the life of the `-s=<session>`, so apply it once, then run the usual `goto` / `snapshot` / `screenshot` commands on the same session.
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Throttling is **Chromium-only** (CDP). It does not work on `firefox` or `webkit` sessions — run those engines unthrottled.
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## Profiles
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| Profile | CPU | Network (down / up / latency) | Models |
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|---|---|---|---|
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| `mid` | 4x | ~1.6 Mbps / 750 Kbps / 150 ms | mid-tier phone (Lighthouse mobile default) |
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| `low` | 6x | ~400 Kbps / 400 Kbps / 400 ms | low-end phone / poor connection |
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| `cpu4` | 4x | full speed | isolate JS cost from network |
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| `cpu6` | 6x | full speed | isolate JS cost from network |
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| `off` | 1x | full speed | reset to normal |
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## Usage
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```bash
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# open a Chromium session, throttle it to a mid-tier phone, then verify as usual
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./scripts/pw-session.sh open lowspec https://5chan.localhost --browser=chrome
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./scripts/pw-throttle.sh lowspec mid
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playwright-cli -s=lowspec snapshot
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playwright-cli -s=lowspec screenshot --filename=lowspec-mid.png
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# tighten to a low-end device
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./scripts/pw-throttle.sh lowspec low
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# isolate JS cost (CPU throttle, full-speed network)
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./scripts/pw-throttle.sh lowspec cpu4
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# reset and finish
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./scripts/pw-throttle.sh lowspec off
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./scripts/pw-session.sh close lowspec
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```
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## Measuring, not guessing
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Throttled numbers are approximations (CDP throttling, not a real device), but the relative difference is the signal. For the initial page load:
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```bash
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playwright-cli -s=lowspec eval "() => Math.round(performance.getEntriesByType('navigation')[0].duration)"
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```
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5chan is a React Router SPA, so in-app navigation does not create a new navigation entry. Time those manually: read `performance.now()` before triggering the route change, then again once the target content appears in the snapshot.
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## Caveats
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- Chromium-only. Skip on Firefox/WebKit sessions; keep those checks unthrottled.
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- Low-spec emulation is a measurement pass, not a machine-resource control. Hold the machine-wide browser slot for the whole pass and close it immediately afterward.
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- The `low` latency is intentionally aggressive; if requests time out, fall back to `mid`.
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- For render/rerender hotspots after a slow result, use the `profile-browsing` skill (it drives `playwright-cli` + react-scan) on the already-throttled session.
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