[PR #5424] [MERGED] [client] fix busy-loop in network monitor routing socket on macOS/BSD #25853

New Issue

saavagebueno · 2026-08-05T07:06:33-04:00

saavagebueno commented

2026-08-05 07:06:33 -04:00

📋 Pull Request Information

Original PR: https://github.com/netbirdio/netbird/pull/5424
Author: @pappz
Created: 2/23/2026
Status: ✅ Merged
Merged: 2/23/2026
Merged by: @pappz

Base: main ← Head: fix/network-monitor-routing-socket-busy-loop

📝 Commits (2)

4da7a60 [client] fix busy-loop in network monitor routing socket on macOS/BSD
8417e6f [client] add fd range validation in waitReadable to prevent out-of-bound errors

📊 Changes

1 file changed (+72 additions, -37 deletions)

View changed files

📝 client/internal/networkmonitor/check_change_common.go (+72 -37)

📄 Description

After system wakeup, the AF_ROUTE socket created by Go's unix.Socket() is non-blocking, causing unix.Read to return EAGAIN immediately and spin at 100% CPU filling the log with thousands of warnings per second.

Replace the tight read loop with a unix.Select call that blocks until the fd is readable, checking ctx cancellation on each 1-second timeout. Fatal errors (EBADF, EINVAL) now return an error instead of looping.

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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)

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Summary by CodeRabbit

Bug Fixes
- Improved network route-change monitoring by replacing busy-wait polling with a blocking wait to reduce CPU usage and latency.
- Added robust error handling and message validation to avoid spurious failures when reading route updates.
- Better handling of route add/delete events, including matching deletions against configured nexthops and periodic context re-checks for reliability.

_{🔄 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/5424 **Author:** [@pappz](https://github.com/pappz) **Created:** 2/23/2026 **Status:** ✅ Merged **Merged:** 2/23/2026 **Merged by:** [@pappz](https://github.com/pappz) **Base:** `main` ← **Head:** `fix/network-monitor-routing-socket-busy-loop` --- ### 📝 Commits (2) - [`4da7a60`](https://github.com/netbirdio/netbird/commit/4da7a60e83583823c5643eb227d03d030fbb7b03) [client] fix busy-loop in network monitor routing socket on macOS/BSD - [`8417e6f`](https://github.com/netbirdio/netbird/commit/8417e6f461abc0b426c5f9014558c1c88edd31a5) [client] add fd range validation in waitReadable to prevent out-of-bound errors ### 📊 Changes **1 file changed** (+72 additions, -37 deletions) <details> <summary>View changed files</summary> 📝 `client/internal/networkmonitor/check_change_common.go` (+72 -37) </details> ### 📄 Description After system wakeup, the AF_ROUTE socket created by Go's unix.Socket() is non-blocking, causing unix.Read to return EAGAIN immediately and spin at 100% CPU filling the log with thousands of warnings per second. Replace the tight read loop with a unix.Select call that blocks until the fd is readable, checking ctx cancellation on each 1-second timeout. Fatal errors (EBADF, EINVAL) now return an error instead of looping. ## 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 network route-change monitoring by replacing busy-wait polling with a blocking wait to reduce CPU usage and latency. * Added robust error handling and message validation to avoid spurious failures when reading route updates. * Better handling of route add/delete events, including matching deletions against configured nexthops and periodic context re-checks for reliability.  --- <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 07:06:33 -04:00

saavagebueno closed this issue

2026-08-05 07:06:34 -04:00

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Reference: DYNR/netbird#25853