contractcourt: only close quit in `Stop` by yyforyongyu · Pull Request #10045 · lightningnetwork/lnd

yyforyongyu · 2025-07-07T12:44:23Z

Make sure we don't prematurely close the quit chans. Fixes the panic,

panic: close of closed channel

goroutine 2397 [running]:
github.com/lightningnetwork/lnd/contractcourt.(*UtxoNursery).Stop(0x400224e340)
    github.com/lightningnetwork/[email protected]/contractcourt/utxonursery.go:332 +0x10c
github.com/lightningnetwork/lnd.cleaner.run({0x4001d9eb80, 0x0?, 0x4000bb17a8?})
    github.com/lightningnetwork/[email protected]/server.go:2187 +0x44
github.com/lightningnetwork/lnd.(*server).Start(0x40012ea708, {0x43764b8, 0x40006fad80})
    github.com/lightningnetwork/[email protected]/server.go:2654 +0xac
github.com/lightningnetwork/lnd.Main.func12()
    github.com/lightningnetwork/[email protected]/lnd.go:761 +0x30
created by github.com/lightningnetwork/lnd.Main in goroutine 356
    github.com/lightningnetwork/[email protected]/lnd.go:760 +0x2df4

This will keep node in panic as the quit chan was closed in Start, and we always call Stop to close the quit, which will cause a panic. This is also because we have changed to cleanup order in 653e2f3.

gemini-code-assist

Summary of Changes

Hello @yyforyongyu, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves a critical panic within the contractcourt package's UtxoNursery component. The fix ensures that the component's quit channel is managed correctly, preventing it from being closed multiple times during startup failures, which previously led to a node-crashing 'close of closed channel' panic. The changes streamline channel lifecycle management by centralizing the quit channel closure to the Stop method.

Highlights

Bug Fix: Panic Prevention: Addressed a critical 'close of closed channel' panic that occurred when the UtxoNursery component failed to start up. Previously, the quit channel was prematurely closed in Start()'s error paths, leading to a panic when Stop() later attempted to close it again.
Channel Lifecycle Management: Refactored the UtxoNursery.Start() method to remove all instances of u.quit channel closure. This ensures that the quit channel is now exclusively closed within the Stop() method, adhering to proper component lifecycle management and preventing double-closure issues.
Improved Error Logging: Replaced the premature close(u.quit) calls with explicit error logging using utxnLog.Errorf before returning an error, providing better diagnostic information during startup failures.

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Code Review

This pull request fixes a potential panic caused by closing the quit channel in multiple places. Centralizing the channel closure within the Stop method eliminates the risk of a double-close.

gemini-code-assist · 2025-07-07T12:45:45Z

contractcourt/utxonursery.go

 	// point forward, we must close the nursery's quit channel if we detect
 	// any failures during startup to ensure they terminate.


The comment above this block is now outdated. It states that the quit channel should be closed if any failures are detected during startup, but the subsequent code no longer does this. Consider updating or removing the comment to avoid confusion.

Make sure we don't prematurely close the `quit` chans.

ziggie1984

LGTM, probably something for 19.2 ?

guggero

LGTM 🎉

yyforyongyu added this to the v0.19.2 milestone Jul 7, 2025

yyforyongyu self-assigned this Jul 7, 2025

yyforyongyu added bug fix size/micro small bug fix or feature, less than 15 mins of review, less than 250 labels Jul 7, 2025

gemini-code-assist bot reviewed Jul 7, 2025

View reviewed changes

contractcourt: only close quit in Stop

2b4c282

Make sure we don't prematurely close the `quit` chans.

yyforyongyu force-pushed the fix-panic branch from 38eb0bf to 736c124 Compare July 7, 2025 12:46

ziggie1984 approved these changes Jul 7, 2025

View reviewed changes

docs: update release docs

9fb0f77

yyforyongyu force-pushed the fix-panic branch from 736c124 to 9fb0f77 Compare July 7, 2025 13:01

guggero approved these changes Jul 7, 2025

View reviewed changes

guggero merged commit b815109 into lightningnetwork:master Jul 7, 2025
37 of 40 checks passed

guggero mentioned this pull request Jul 7, 2025

release: create v0.19.2-rc2 branch #10047

Merged

yyforyongyu deleted the fix-panic branch July 8, 2025 04:23

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contractcourt: only close quit in `Stop`#10045

contractcourt: only close quit in `Stop`#10045
guggero merged 2 commits intolightningnetwork:masterfrom
yyforyongyu:fix-panic

yyforyongyu commented Jul 7, 2025 •

edited

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		// point forward, we must close the nursery's quit channel if we detect
		// any failures during startup to ensure they terminate.

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yyforyongyu commented Jul 7, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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yyforyongyu commented Jul 7, 2025 •

edited

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