feat: use different snappy implementations for different topics #8670

twoeths · 2025-12-05T03:24:32Z

Motivation

snappy-wasm introduced different behaviour on different nodes: great on non-sas nodes but introduced performance regression on sas nodes, see feat: use snappy-wasm (#6483) #8647

Description

bring snappy-js implementation to lodestar
- a little improvement: use Buffer.allocUnsafe() there
use snappy-js for beacon_attestation topic type and snappy-wasm for other topics
this is deployed to feat3

gemini-code-assist · 2025-12-05T03:24:50Z

Summary of Changes

Hello @twoeths, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a strategic change to the Snappy decompression mechanism within the beacon node to resolve a performance bottleneck identified on SAS nodes. By selectively applying snappy-js for beacon_attestation messages and retaining snappy-wasm for other data, the system aims to optimize decompression efficiency. The changes involve integrating a new library, refactoring core data transformation logic, and ensuring robust error handling and test coverage for the new hybrid approach.

Highlights

Performance Improvement: Addresses a performance regression on SAS nodes caused by snappy-wasm by introducing a hybrid compression strategy.
Hybrid Snappy Decompression: Implements a dynamic selection mechanism to use snappy-js for beacon_attestation topic types (typically smaller payloads) and snappy-wasm for all other topics.
New Dependency: Adds snappyjs as a new dependency to the beacon-node package.
Refactored Decompression Logic: The inboundTransform function in encoding.ts has been refactored to utilize a new ISnappyDecompressor interface, allowing for different Snappy implementations to be used based on the topic type. Error messages for decompression failures have also been enhanced.
New Snappy-JS Implementation: Introduces a complete snappy-js implementation, including SnappyCompressor, SnappyDecompressor, and associated error handling, within the project.
Unit Tests: Adds new unit tests to validate the correct functioning of the hybrid snappy decompression logic across various data lengths and gossip types.

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Code Review

This pull request introduces snappyjs for decompressing beacon_attestation messages to address performance regressions on certain nodes, while snappy-wasm is retained for other message types and all compression tasks. The changes are well-structured, using a decompressor interface and a factory function for selecting the appropriate implementation. My review focuses on improving the consistency and error handling between the two snappy implementations to make the new abstraction more robust.

packages/beacon-node/src/network/gossip/snappy/snappy-wasm.ts

packages/beacon-node/src/network/gossip/encoding.ts

wemeetagain · 2025-12-05T03:51:29Z

packages/beacon-node/src/network/gossip/snappy/index.ts

+ */
+export function getSnappyDecompressor(topicType: GossipType, data: Uint8Array): ISnappyDecompressor {
+  switch (topicType) {
+    case GossipType.beacon_attestation:


also aggregate and proof?

I switched to use snappy-wasm for data_column_sidecar and beacon_block
for others use snappy-js

wemeetagain · 2025-12-05T03:55:43Z

packages/beacon-node/src/network/gossip/snappy/snappy-js/index.ts

@@ -0,0 +1,56 @@
+import {SnappyCompressor} from "./compressor.js";


nice, this is snappyjs but converted to typescript?

should leave a comment here linking back to the upstream,
eg, // Based on snappyjs - https://github.com/zhipeng-jia/snappyjs

wemeetagain · 2025-12-05T03:58:57Z

packages/beacon-node/src/network/gossip/snappy/snappy-js/decompressor.ts

+    return -1;
+  }
+
+  uncompressInto(outBuffer: Uint8Array): boolean {


and we are now using this, which was previously hidden by our incomplete manually-crafted types

wemeetagain

can you update the snappy benchmarks with this impl of snappyjs?

twoeths · 2025-12-05T07:49:40Z

The high MarkSweepCompact gc issue on feat3 is still high until I switched back to Buffer.alloc()

twoeths added 3 commits December 5, 2025 09:08

feat: add snappyjs implementation in ts

4419e35

feat: implement ISnappyDecompressor interface

cbe7cfa

feat: use different uncompressor based on topic type

e717d37

twoeths requested a review from a team as a code owner December 5, 2025 03:24

twoeths changed the title ~~Te/cayman/snappy~~ feat: use different snappy implementations for different topics Dec 5, 2025

gemini-code-assist bot reviewed Dec 5, 2025

View reviewed changes

packages/beacon-node/src/network/gossip/snappy/snappy-wasm.ts Show resolved Hide resolved

packages/beacon-node/src/network/gossip/snappy/snappy-wasm.ts Show resolved Hide resolved

packages/beacon-node/src/network/gossip/encoding.ts Show resolved Hide resolved

twoeths added 2 commits December 5, 2025 10:29

fix: remove snappy-js

3f091e8

fix: make consistent behaviour across implementations

c94ede7

wemeetagain reviewed Dec 5, 2025

View reviewed changes

twoeths added 3 commits December 5, 2025 11:45

fix: use snappy-wasm for beacon_block and data_column_sidecar only

2d4de6a

fix: use Buffer.alloc()

a74d316

fix: update snappy benchmark using ISnappyDecompressor interface

95416e8

twoeths mentioned this pull request Dec 5, 2025

fix: use Buffer.alloc() with snappy-wasm #8671

Open

chore: link to snappy-js upstream repo

732860c

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twoeths commented Dec 5, 2025 •

edited

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		@@ -0,0 +1,56 @@
		import {SnappyCompressor} from "./compressor.js";

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twoeths commented Dec 5, 2025 •

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