1ccece0f78
Bounded DeliveredEvent queues reduce memory usage, but they can deadlock under load. Two common scenarios trigger deadlocks when the number of events published in a short period exceeds twice the queue capacity (there's a PublishedEvent queue of the same size): - a subscriber tries to acquire the same mutex as held by a publisher, or - a subscriber for A events publishes B events Avoiding these scenarios is not practical and would limit eventbus usefulness and reduce its adoption, pushing us back to callbacks and other legacy mechanisms. These deadlocks already occurred in customer devices, dev machines, and tests. They also make it harder to identify and fix slow subscribers and similar issues we have been seeing recently. Choosing an arbitrary large fixed queue capacity would only mask the problem. A client running on a sufficiently large and complex customer environment can exceed any meaningful constant limit, since event volume depends on the number of peers and other factors. Behavior also changes based on scheduling of publishers and subscribers by the Go runtime, OS, and hardware, as the issue is essentially a race between publishers and subscribers. Additionally, on lower-end devices, an unreasonably high constant capacity is practically the same as using unbounded queues. Therefore, this PR changes the event queue implementation to be unbounded by default. The PublishedEvent queue keeps its existing capacity of 16 items, while subscribers' DeliveredEvent queues become unbounded. This change fixes known deadlocks and makes the system stable under load, at the cost of higher potential memory usage, including cases where a queue grows during an event burst and does not shrink when load decreases. Further improvements can be implemented in the future as needed. Fixes #17973 Fixes #18012 Signed-off-by: Nick Khyl <nickk@tailscale.com>
Tailscale
Private WireGuard® networks made easy
Overview
This repository contains the majority of Tailscale's open source code.
Notably, it includes the tailscaled daemon and
the tailscale CLI tool. The tailscaled daemon runs on Linux, Windows,
macOS, and to varying degrees
on FreeBSD and OpenBSD. The Tailscale iOS and Android apps use this repo's
code, but this repo doesn't contain the mobile GUI code.
Other Tailscale repos of note:
- the Android app is at https://github.com/tailscale/tailscale-android
- the Synology package is at https://github.com/tailscale/tailscale-synology
- the QNAP package is at https://github.com/tailscale/tailscale-qpkg
- the Chocolatey packaging is at https://github.com/tailscale/tailscale-chocolatey
For background on which parts of Tailscale are open source and why, see https://tailscale.com/opensource/.
Using
We serve packages for a variety of distros and platforms at https://pkgs.tailscale.com.
Other clients
The macOS, iOS, and Windows clients use the code in this repository but additionally include small GUI wrappers. The GUI wrappers on non-open source platforms are themselves not open source.
Building
We always require the latest Go release, currently Go 1.25. (While we build releases with our Go fork, its use is not required.)
go install tailscale.com/cmd/tailscale{,d}
If you're packaging Tailscale for distribution, use build_dist.sh
instead, to burn commit IDs and version info into the binaries:
./build_dist.sh tailscale.com/cmd/tailscale
./build_dist.sh tailscale.com/cmd/tailscaled
If your distro has conventions that preclude the use of
build_dist.sh, please do the equivalent of what it does in your
distro's way, so that bug reports contain useful version information.
Bugs
Please file any issues about this code or the hosted service on the issue tracker.
Contributing
PRs welcome! But please file bugs. Commit messages should reference bugs.
We require Developer Certificate of
Origin
Signed-off-by lines in commits.
See commit-messages.md (or skim git log) for our commit message style.
About Us
Tailscale is primarily developed by the people at https://github.com/orgs/tailscale/people. For other contributors, see:
- https://github.com/tailscale/tailscale/graphs/contributors
- https://github.com/tailscale/tailscale-android/graphs/contributors
Legal
WireGuard is a registered trademark of Jason A. Donenfeld.