Files
firezone/rust/connlib/bufferpool/Cargo.toml
Thomas Eizinger e81dc452f7 refactor(connlib): use a lock-free queue for the buffer pool (#9989)
We use several buffer pools across `connlib` that are all backed by the
same buffer-pool library. Within that library, we currently use another
object-pool library to provide the actual pooling functionality.

Benchmarking has shown that spend quite a bit of time (a few % of total
CPU time), fighting for the lock to either add or remote a buffer from
the pool. This is unnecessary. By using a queue, we can remove buffers
from the front and add buffers at the back, both of which can be
implemented in a lock-free way such that they don't contend.

Using the well-known `crossbeam-queue` library, we have such a queue
directly available.

I wasn't able to directly measure a performance gain in terms of
throughput. What we can measure though, is how much time we spend
dealing with our buffer pool vs everything else. If we compare the
`perf` outputs that were recorded during an `iperf` run each, we can see
that we spend about 60% less time dealing with the buffer pool than we
did before.

|Before|After|
|---|---|
|<img width="1982" height="553" alt="Screenshot From 2025-07-24
20-27-50"
src="https://github.com/user-attachments/assets/1698f28b-5821-456f-95fa-d6f85d901920"
/>|<img width="1982" height="553" alt="Screenshot From 2025-07-24
20-27-53"
src="https://github.com/user-attachments/assets/4f26a2d1-03e3-4c0d-84da-82c53b9761dd"
/>|

The number in the thousands on the left is how often the respective
function was the currently executing function during the profiling run.

Resolves: #9972
2025-07-28 21:39:11 +00:00

22 lines
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TOML

[package]
name = "bufferpool"
version = "0.1.0"
edition = { workspace = true }
license = { workspace = true }
[lib]
path = "lib.rs"
[dependencies]
bytes = { workspace = true }
crossbeam-queue = { workspace = true }
opentelemetry = { workspace = true, features = ["metrics"] }
tracing = { workspace = true }
[dev-dependencies]
opentelemetry_sdk = { workspace = true, features = ["testing", "metrics"] }
tokio = { workspace = true, features = ["macros", "rt"] }
[lints]
workspace = true