[PR #6397] [MERGED] [client, proxy] cancel context before stopping engine on embedded client #28162

New Issue

saavagebueno · 2026-08-05T08:05:53-04:00

saavagebueno commented

2026-08-05 08:05:53 -04:00

📋 Pull Request Information

Original PR: https://github.com/netbirdio/netbird/pull/6397
Author: @mlsmaycon
Created: 6/10/2026
Status: ✅ Merged
Merged: 6/10/2026
Merged by: @mlsmaycon

Base: main ← Head: fix/embedded-client-deadlock

📝 Commits (2)

eee33ec [client, proxy] cancel context before stopping engine on embedded client
c9bfe51 add missing error check for NewIntegratedValidator

📊 Changes

2 files changed (+172 additions, -0 deletions)

View changed files

📝 client/embed/embed.go (+4 -0)
➕ client/embed/embed_test.go (+168 -0)

📄 Description

Describe your changes

Engine.Start takes syncMsgMux with a deferred unlock (engine.go:445) and parks in receiveSignalEvents → WaitStreamConnected (engine.go:1762), which only wakes on
signal-stream connect or client-context cancellation.
When signal never connects, the 30s startup timeout fires and embed.Client.Start's rollback (embed.go:281) called client.Stop() → Engine.Stop, which blocks acquiring
syncMsgMux (engine.go:318). The cancel() that would unpark Start was deferred until Start returned — permanent cycle. RemovePeer calls (g43/g385) then queue behind the
lifecycle mutex.
Notably, embed.Client.Stop and the daemon's cleanupConnection both cancel before stopping — the startup rollback was the only path that didn't.
Engine.Start takes syncMsgMux with a deferred unlock (engine.go:445) and parks in receiveSignalEvents → WaitStreamConnected (engine.go:1762), which only wakes on
signal-stream connect or client-context cancellation.
When signal never connects, the 30s startup timeout fires and embed.Client.Start's rollback (embed.go:281) called client.Stop() → Engine.Stop, which blocks acquiring
syncMsgMux (engine.go:318). The cancel() that would unpark Start was deferred until Start returned — permanent cycle. RemovePeer calls (g43/g385) then queue behind the
lifecycle mutex.
Notably, embed.Client.Stop and the daemon's cleanupConnection both cancel before stopping — the startup rollback was the only path that didn't.

Issue ticket number and link

Stack

Checklist

Is it a bug fix
Is a typo/documentation fix
Is a feature enhancement
It is a refactor
Created tests that fail without the change (if possible)
This change does not modify the public API, gRPC protocols, functionality behavior, CLI / service flags, or introduce a new feature — OR I have discussed it with the NetBird team beforehand (link the issue / Slack thread in the description). See CONTRIBUTING.md.

By submitting this pull request, you confirm that you have read and agree to the terms of the Contributor License Agreement.

Documentation

Select exactly one:

I added/updated documentation for this change
Documentation is not needed for this change (explain why)

Docs PR URL (required if "docs added" is checked)

Paste the PR link from https://github.com/netbirdio/docs here:

https://github.com/netbirdio/docs/pull/__

Summary by CodeRabbit

Bug Fixes
- Resolved a potential deadlock during embedded client startup when startup times out; startup is now explicitly canceled and resources are cleanly shut down on deadline.
Tests
- Added a test that reproduces and verifies correct timeout and rollback behavior for embedded client startup.

_{🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.}

## 📋 Pull Request Information **Original PR:** https://github.com/netbirdio/netbird/pull/6397 **Author:** [@mlsmaycon](https://github.com/mlsmaycon) **Created:** 6/10/2026 **Status:** ✅ Merged **Merged:** 6/10/2026 **Merged by:** [@mlsmaycon](https://github.com/mlsmaycon) **Base:** `main` ← **Head:** `fix/embedded-client-deadlock` --- ### 📝 Commits (2) - [`eee33ec`](https://github.com/netbirdio/netbird/commit/eee33ec75fd5c59bf3eb7e0c5ce17fdf05857326) [client, proxy] cancel context before stopping engine on embedded client - [`c9bfe51`](https://github.com/netbirdio/netbird/commit/c9bfe51843fd3d7f4fc261d340556d9e901c297b) add missing error check for NewIntegratedValidator ### 📊 Changes **2 files changed** (+172 additions, -0 deletions) <details> <summary>View changed files</summary> 📝 `client/embed/embed.go` (+4 -0) ➕ `client/embed/embed_test.go` (+168 -0) </details> ### 📄 Description ## Describe your changes - Engine.Start takes syncMsgMux with a deferred unlock (engine.go:445) and parks in receiveSignalEvents → WaitStreamConnected (engine.go:1762), which only wakes on signal-stream connect or client-context cancellation. - When signal never connects, the 30s startup timeout fires and embed.Client.Start's rollback (embed.go:281) called client.Stop() → Engine.Stop, which blocks acquiring syncMsgMux (engine.go:318). The cancel() that would unpark Start was deferred until Start returned — permanent cycle. RemovePeer calls (g43/g385) then queue behind the lifecycle mutex. - Notably, embed.Client.Stop and the daemon's cleanupConnection both cancel before stopping — the startup rollback was the only path that didn't. - Engine.Start takes syncMsgMux with a deferred unlock (engine.go:445) and parks in receiveSignalEvents → WaitStreamConnected (engine.go:1762), which only wakes on signal-stream connect or client-context cancellation. - When signal never connects, the 30s startup timeout fires and embed.Client.Start's rollback (embed.go:281) called client.Stop() → Engine.Stop, which blocks acquiring syncMsgMux (engine.go:318). The cancel() that would unpark Start was deferred until Start returned — permanent cycle. RemovePeer calls (g43/g385) then queue behind the lifecycle mutex. - Notably, embed.Client.Stop and the daemon's cleanupConnection both cancel before stopping — the startup rollback was the only path that didn't. ## Issue ticket number and link ## Stack  ### Checklist - [x] Is it a bug fix - [ ] Is a typo/documentation fix - [ ] Is a feature enhancement - [ ] It is a refactor - [x] Created tests that fail without the change (if possible) - [ ] This change does **not** modify the public API, gRPC protocols, functionality behavior, CLI / service flags, or introduce a new feature — **OR** I have discussed it with the NetBird team beforehand (link the issue / Slack thread in the description). See [CONTRIBUTING.md](https://github.com/netbirdio/netbird/blob/main/CONTRIBUTING.md#discuss-changes-with-the-netbird-team-first). > By submitting this pull request, you confirm that you have read and agree to the terms of the [Contributor License Agreement](https://github.com/netbirdio/netbird/blob/main/CONTRIBUTOR_LICENSE_AGREEMENT.md). ## Documentation Select exactly one: - [ ] I added/updated documentation for this change - [x] Documentation is **not needed** for this change (explain why) ### Docs PR URL (required if "docs added" is checked) Paste the PR link from https://github.com/netbirdio/docs here: https://github.com/netbirdio/docs/pull/__  ## Summary by CodeRabbit * **Bug Fixes** * Resolved a potential deadlock during embedded client startup when startup times out; startup is now explicitly canceled and resources are cleanly shut down on deadline. * **Tests** * Added a test that reproduces and verifies correct timeout and rollback behavior for embedded client startup.  --- <sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>

saavagebueno added the pull-request label 2026-08-05 08:05:53 -04:00

saavagebueno closed this issue

2026-08-05 08:05:54 -04:00

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Reference: DYNR/netbird#28162