gui: the window gives memory back once it has been left alone by donislawdev · Pull Request #134 · donislawdev/TestingFilesGenerator

donislawdev · 2026-09-24T08:16:52Z

What changes for the user

After a spell of work the window kept about 200 MB for as long as it stood idle. About a minute and a half after the last thing done in it, it now gives back what it no longer uses: 215 MB down to 129 MB in the real window. Nothing on the screen moves when it does.

Why the memory stayed

Fyne 2.8.1 destroys the renderers of objects that have left the screen only while drawing a frame (internal/cache/base.go, Clean), and an idle window draws no frames (internal/driver/glfw/loop.go).
Go returns freed pages slowly, and in the quiet it collects only every two minutes. Measured over five minutes: the process stayed at 189-206 MB.

What changed

internal/gui/window/tidy.go waits out one quiet period for the whole window. Every reading of the form restarts the wait: watchedSettle, formerly countedSettle, now also tells runner.touched.

After 70 s, which is past the minute Fyne keeps a renderer, the canvas root is marked for redrawing. This touches no widget. The scroll offset, the focused field, and what every box, menu and switch holds (including the cursor position) were compared before and after, and they were identical.
12 s later, which is past the ten seconds between two of Fyne's cleans, memory is given back with go debug.FreeOSMemory().
It runs off the window's thread because one of ten calls on it took 2491 ms, for a reason that was not found. The other nine took 4.6-16.2 ms.
Nothing is given back while a run owns the window. The wait then starts again. It happens once per quiet period.

Concurrency: a gap found and closed

The concurrency guard's scan did not see time.AfterFunc. The window's clock (internal/gui/run_cgo.go) had been calling back on a timer's goroutine without being declared.

The scan now sees time.AfterFunc. TestTheConcurrencyScanSeesEachKindItLooksFor tests it against source written inside the test.
A declared file that no longer contains any concurrency is now red, so removing the go in front of FreeOSMemory cannot pass unnoticed.
run_cgo.go and tidy.go are declared, and both are on the race job's watched list in .github/workflows/ci.yml.

This PR changes a workflow file, so it needs merging from the browser. It also triggers the race job, which took 32m 47s on #131 against a 40-minute ceiling.

Guards

TestTheWindowGivesMemoryBackOnceItHasBeenLeftAlone: the order and both waits.
TestSomethingDoneDuringTheWaitStartsTheQuietOver: a release already waiting is called off.
TestNoMemoryIsGivenBackWhileWorkIsGoing: a run is held open while the check runs.

They run on a quiet clock in the guards' host. It keeps a list of requests and is kept apart from Later, whose single slot the busy face uses. Eight new mutation entries, all caught. One existing entry was re-pointed onto watchedSettle and caught again.

Not checked

A minimised window draws no frames, so it is expected to give back only what Go holds.
Linux and macOS.
A run longer than 82 s in the real window.

🤖 Generated with Claude Code

Summary by CodeRabbit

New Features
- After roughly 90 seconds without activity, the window releases unused memory while keeping the display unchanged. In one measured case, memory usage fell from 215 MB to 129 MB.
- A minimized window may release less memory, since memory is freed during drawing. If activity resumes or work is in progress, memory release waits until the window has been idle again.

After a spell of work the process kept about 200 MB for as long as the window stood idle. Fyne destroys the renderers of objects that left the screen only while drawing a frame, and an idle window draws none. Go also returns freed pages slowly and collects in the quiet only every two minutes. tidy.go waits out one quiet for the whole window. Every reading of the form restarts it (watchedSettle, formerly countedSettle, tells runner.touched). After 70 s - past the minute Fyne keeps a renderer - the canvas root is marked for redrawing, which touches no widget: the scroll, the focus and every box, menu and switch were compared either side and were the same. 12 s later - past the ten seconds between two of Fyne's cleans - memory is given back with go debug.FreeOSMemory(). That runs off the window's thread because one of ten calls on it took 2491 ms. Nothing is given back while a run owns the window, and the wait then starts again. In the real window, with no nudge from the probe: 215 MB -> 129 MB between 80 and 90 s of quiet. The concurrency scan did not see time.AfterFunc, so the window's clock in internal/gui/run_cgo.go had been calling back on a timer's goroutine undeclared. The scan now sees it and is asked of source written in the test. A declared file with no concurrency left is red. run_cgo.go and tidy.go are declared and on the race job's watched list. Guards: TestTheWindowGivesMemoryBackOnceItHasBeenLeftAlone, TestSomethingDoneDuringTheWaitStartsTheQuietOver, TestNoMemoryIsGivenBackWhileWorkIsGoing, on a quiet clock in the guards' host kept apart from the busy face's, and TestTheConcurrencyScanSeesEachKindItLooksFor. Co-Authored-By: Claude Opus 5.5 <[email protected]>

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📝 Walkthrough

Walkthrough

Screen runners now track form reads and use them to reset a per-window idle timer. After 70 seconds, the window refreshes canvas content and schedules memory release 12 seconds later. If a screen is busy, the quiet period restarts; otherwise, the host hook runs and Go requests memory reclamation asynchronously.

Changes

Window memory reclamation

Layer / File(s)	Summary
Track screen activity `internal/gui/window/open.go`, `internal/gui/window/run.go`, `internal/gui/window/generate.go`, `internal/gui/window/preset.go`, `internal/gui/window/recipe.go`	`watchedSettle` calls the runner’s `touched` callback when it reads a form. Each screen constructor uses this wrapper.
Schedule idle memory reclamation `internal/gui/window/tidy.go`, `internal/gui/window/open.go`, `CHANGELOG.md`	A per-window timer waits 70 seconds after activity, refreshes canvas content when available, then waits 12 seconds before release. The timer restarts if a screen is busy. The changelog records measured memory usage and minimized-window behavior.
Test and detect concurrency changes `internal/guard/*`, `.github/workflows/ci.yml`	Tests cover timer ordering, resets, and busy screens. The concurrency guard detects `time.AfterFunc` and verifies allowlisted files contain concurrency. The CI watched-file list includes the cleanup implementation.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant ScreenRunner
  participant tidy
  participant Host
  participant Canvas
  participant FreeOSMemory
  ScreenRunner->>tidy: touched callback after form read
  tidy->>Host: schedule 70-second quiet wait
  tidy->>Canvas: refresh content after quiet wait, when available
  tidy->>Host: schedule 12-second release wait
  tidy->>Host: call ReleasingMemory when screens are not busy
  tidy->>FreeOSMemory: request asynchronous memory release

Suggested labels: bug, performance, ui

Merge Risk: 🟡 Moderate · up to 9331b

Memory cleanup can occur after recent input instead of waiting for a full quiet period. Fix timer cancellation before merging; also correct the guard and the user-facing description.

🚥 Pre-merge checks | ✅ 12 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Desktop Robustness	⚠️ Warning	The PR adds window-owned delayed work that can outlive the window. `Open` adds `quiet` to the close `Stop()` list, but `tidy.Stop()` only stops the current timer. The real `Host.Later` uses `time.Afte…	Give tidy callbacks a closed/generation state. Increment or invalidate that state in `Stop()`, and make both `frame` and `release` return when their captured generation is stale or the window is closed. Prevent `touch()` from scheduling new…
No Resource Leaks	⚠️ Warning	The new quiet-cleanup timer chain has an uncancelled stale-callback path. `desktop.Later` uses `time.AfterFunc` and queues the callback with `fyne.Do` (`internal/gui/run_cgo.go:94-96`). `tidy.Stop` ca…	Add a stopped/generation state to `tidy`. Increment or invalidate it in `touch` and `Stop`, and make both `frame` and `release` return without refreshing or scheduling another timer when their generation is stale or the tidy is stopped. Kee…

✅ Passed checks (12 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main user-visible change: the GUI window releases memory after it has been left idle. It is specific, plain-language, and within the 140-character limit.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Tests For Changed Behavior	✅ Passed	The PR adds non-UI runtime behavior in `internal/gui/window/tidy.go` and wires it through `open.go` and `watchedSettle`. It also adds three tests in `internal/guard/tidy_test.go` covering the quiet an…
No Secrets Or Debug Leftovers	✅ Passed	The pull-request diff adds no CLAUDE.md, CLAUDE.local.md, AGENTS.md, .claude/, or .env files. Added-line scans found no credentials, tokens, private URLs, personal e-mails, machine or user names, hard…
No Hardcoded Ui Styling	✅ Passed	The PR changes Fyne GUI code, but the changed lines only add quiet-period cleanup, form-read callbacks, timer durations, and canvas refresh logic. The diff adds no literal colors, fonts, font sizes, m…
No Obvious Performance Problems	✅ Passed	No clear performance problem matches the check. The new cleanup schedules one 70-second quiet timer and one 12-second follow-up; it does not poll or refresh data repeatedly. The single canvas refresh …
Safe File Parsing	✅ Passed	No targeted file parsing or export was introduced. The PR changes GUI timing and memory cleanup. The only parser use is the existing guard’s Go AST `go/parser.ParseFile` over Go source and in-memory t…
System Changes Are Reversible	✅ Passed	The PR does not add or change any qualifying system-state modification. The new code refreshes the Fyne canvas, schedules timers, and calls `debug.FreeOSMemory()` to reclaim process memory. It does no…
Clear User-Facing Text	✅ Passed	PASS: The changed GUI code adds no new user-facing labels, buttons, tooltips, dialogs, confirmations, or error messages. It only changes cleanup behavior and internal callbacks. The added CHANGELOG en…
Scope, Duplication And Docs	✅ Passed	The authoritative diff is scoped to the described quiet-period memory cleanup, its runner wiring, concurrency detection/CI coverage, focused guards, and a renamed test diagnostic. The PR description c…

Full details: Desktop Robustness

Explanation

The PR adds window-owned delayed work that can outlive the window. Open adds quiet to the close Stop() list, but tidy.Stop() only stops the current timer. The real Host.Later uses time.AfterFunc and queues callbacks with fyne.Do; the repository already documents and tests that a callback queued before cancellation still runs. If frame is queued when close occurs, tidy.frame() still refreshes the canvas and schedules release() after h.Close(). release() can then start go debug.FreeOSMemory() with no lifecycle tracking. The new tidy tests do not cover close or queued callbacks.

Resolution

Give tidy callbacks a closed/generation state. Increment or invalidate that state in Stop(), and make both frame and release return when their captured generation is stale or the window is closed. Prevent touch() from scheduling new work after Stop(). Track any active FreeOSMemory goroutine and wait for it, or otherwise ensure it cannot start or remain active after the close path completes. Add a guard that queues a tidy callback, closes the window, and verifies that no refresh, follow-up timer, release hook, or cleanup goroutine runs after close.

Full details: No Resource Leaks

Explanation

The new quiet-cleanup timer chain has an uncancelled stale-callback path. desktop.Later uses time.AfterFunc and queues the callback with fyne.Do (internal/gui/run_cgo.go:94-96). tidy.Stop cancels only the current callOff (internal/gui/window/tidy.go:106-113). If a timer has already queued frame, Stop cannot remove that queued callback. The queued frame still runs and schedules a new 12-second t.later(..., t.release) timer (tidy.go:118-123), even after window shutdown. During normal activity, the stale frame also overwrites the cancellation handle for the newer quiet timer, leaving that timer orphaned. Repeated boundary events can therefore accumulate delayed callbacks and cause cleanup after the window is closed. The added fake-clock tests do not model callbacks that remain queued after cancellation. The one-shot go debug.FreeOSMemory() is finite and is not the main leak.

Resolution

Add a stopped/generation state to tidy. Increment or invalidate it in touch and Stop, and make both frame and release return without refreshing or scheduling another timer when their generation is stale or the tidy is stopped. Keep cancellation handles valid for the current generation. Add a test that queues a timer callback, calls Stop or starts a new quiet period, then runs the stale callback and verifies that it creates no release timer and no post-close cleanup.

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Actionable comments posted: 3

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Inline comments:
In `@CHANGELOG.md`:
- Around line 497-503: Update the changelog description to say the idle timer
follows form changes and the end of the last run, rather than implying it resets
after any activity. Keep the existing timing and memory measurements unchanged.

In `@internal/guard/concurrency_test.go`:
- Around line 138-150: Update the concurrency allowlist validation in the test
around mayBeConcurrent and idle to check every declared path exists under
repoRoot(t), including files omitted by packages(t); add missing paths to idle
so stale declarations fail the existing check.

In `@internal/gui/window/tidy.go`:
- Around line 118-130: Add a generation token to the tidy wait callbacks so a
stale frame queued before cancellation exits before modifying callOff or
scheduling release. Update tidy.frame and the cancellation/touch flow to capture
and validate the token, invalidating prior callbacks when a new wait begins;
preserve the active timer behavior.

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Reviewing files that changed from the base of the PR and between 552e30b and 9331b58.

📒 Files selected for processing (12)

.github/workflows/ci.yml
CHANGELOG.md
internal/guard/concurrency_test.go
internal/guard/settleonce_test.go
internal/guard/tidy_test.go
internal/guard/window_test.go
internal/gui/window/generate.go
internal/gui/window/open.go
internal/gui/window/preset.go
internal/gui/window/recipe.go
internal/gui/window/run.go
internal/gui/window/tidy.go

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