[PR #4891] [MERGED] [client] Fix engine shutdown deadlock and sync-signal message handling races #26559

New Issue

saavagebueno · 2026-08-05T07:07:29-04:00

saavagebueno commented

2026-08-05 07:07:29 -04:00

📋 Pull Request Information

Original PR: https://github.com/netbirdio/netbird/pull/4891
Author: @pappz
Created: 12/1/2025
Status: ✅ Merged
Merged: 12/4/2025
Merged by: @pappz

Base: main ← Head: fix/engine-stop-deadlock

📝 Commits (7)

289fe33 Fix engine shutdown deadlock and message handling races
890b7be Fix lint
15f6533 Revert context from Stop. Unfortunately it covers potential issues.
b81465d Remove comment
c2b9c51 Merge remote-tracking branch 'origin/main' into fix/engine-stop-deadlock
e9ce717 Add error logs
68e7526 Add more logs

📊 Changes

3 files changed (+31 additions, -15 deletions)

View changed files

📝 client/internal/connect.go (+8 -5)
📝 client/internal/engine.go (+21 -10)
📝 client/server/server.go (+2 -0)

📄 Description

Release syncMsgMux before waiting for shutdownWg to prevent deadlock
Check context inside lock in handleSync and receiveSignalEvents
Prevents nil pointer access when messages arrive during engine stop

Describe your changes

Issue ticket number and link

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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)

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
- Improved engine startup/shutdown ordering to reduce races and increase stability.
- Added context-aware shutdown checks and timeouts to prevent hangs and avoid work during termination.
- Strengthened stop sequencing and guards to make shutdown idempotent and more thread-safe.
Chores
- Internal cleanup, inline error handling, and added diagnostics/comments for clearer troubleshooting.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

_{🔄 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/4891 **Author:** [@pappz](https://github.com/pappz) **Created:** 12/1/2025 **Status:** ✅ Merged **Merged:** 12/4/2025 **Merged by:** [@pappz](https://github.com/pappz) **Base:** `main` ← **Head:** `fix/engine-stop-deadlock` --- ### 📝 Commits (7) - [`289fe33`](https://github.com/netbirdio/netbird/commit/289fe33866f54dc3142ca039d58455522a3dfc51) Fix engine shutdown deadlock and message handling races - [`890b7be`](https://github.com/netbirdio/netbird/commit/890b7be33ccd0b4719004ee0aadbfd38b44db7e0) Fix lint - [`15f6533`](https://github.com/netbirdio/netbird/commit/15f65338740bce5ac454c9e08f4f0a8d49a7cb44) Revert context from Stop. Unfortunately it covers potential issues. - [`b81465d`](https://github.com/netbirdio/netbird/commit/b81465d4eee511c886adae5023cf1d2f7ab40d23) Remove comment - [`c2b9c51`](https://github.com/netbirdio/netbird/commit/c2b9c518309ba58c37c4b220a5bade2faeed0332) Merge remote-tracking branch 'origin/main' into fix/engine-stop-deadlock - [`e9ce717`](https://github.com/netbirdio/netbird/commit/e9ce717a9fbaa75c3795f47161920eb6cc0f04e9) Add error logs - [`68e7526`](https://github.com/netbirdio/netbird/commit/68e75264889bc5594190cb5f5a4ef25cfe01be55) Add more logs ### 📊 Changes **3 files changed** (+31 additions, -15 deletions) <details> <summary>View changed files</summary> 📝 `client/internal/connect.go` (+8 -5) 📝 `client/internal/engine.go` (+21 -10) 📝 `client/server/server.go` (+2 -0) </details> ### 📄 Description - Release syncMsgMux before waiting for shutdownWg to prevent deadlock - Check context inside lock in handleSync and receiveSignalEvents - Prevents nil pointer access when messages arrive during engine stop ## Describe your changes ## 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 - [ ] Created tests that fail without the change (if possible) > 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** * Improved engine startup/shutdown ordering to reduce races and increase stability. * Added context-aware shutdown checks and timeouts to prevent hangs and avoid work during termination. * Strengthened stop sequencing and guards to make shutdown idempotent and more thread-safe. * **Chores** * Internal cleanup, inline error handling, and added diagnostics/comments for clearer troubleshooting. <sub>✏️ Tip: You can customize this high-level summary in your review settings.</sub>  --- <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 07:07:29 -04:00

saavagebueno closed this issue

2026-08-05 07:07:30 -04:00

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Reference: DYNR/netbird#26559