reth-bb

A modified reth node for benchmarking big block execution — payloads that merge transactions from multiple consecutive blocks into a single block to simulate high-gas workloads.

Not for production use. reth-bb disables some consensus-related validations to allow artificially large blocks. It is intended solely for performance benchmarking.

How it works

reth-bb extends the standard Ethereum node with:

Multi-segment execution — a custom reth_newPayload handler that accepts optional BigBlockData alongside the payload. When present, the block is executed in multiple segments, each with its own EVM environment (matching the original blocks that were merged).
Relaxed consensus — the gas-limit bound-divisor check and blob gas validation are skipped, since merged blocks exceed single-block limits.

Quick start

The full workflow has five steps: build reth-bb, install txgen tools, extract big-block payloads, start reth-bb, and replay the payloads.

Prerequisites

A synced reth datadir for the target chain (e.g. hoodi)
Rust toolchain
An archive RPC endpoint that supports debug_getRawBlock

1. Build reth-bb

bash

cargo build --profile profiling -p reth-bb

2. Install txgen tools

Install txgen-ethereum for big-block extraction and bench for Engine API replay from tempoxyz/txgen:

bash

cargo install --git https://github.com/tempoxyz/txgen txgen-ethereum --locked
cargo install --git https://github.com/tempoxyz/txgen bench-cli --locked

3. Extract big-block payloads

Merge source blocks into synthetic big-block payloads, starting at the block following the one the node is currently synced to (i.e. the next block the node would process):

bash

txgen-ethereum extract-big-blocks \
    --rpc https://rpc.hoodi.ethpandaops.io \
    --from 910020 \
    --count 5 \
    --target-gas 2G \
    --output /tmp/big-blocks.ndjson

This produces an NDJSON file containing one reth-bb-compatible big-block payload per line. --target-gas accepts bare units or K, M, G suffixes.

4. Start reth-bb

bash

reth-bb node \
    --datadir /data/reth/hoodi \
    --chain hoodi \
    --http --http.api debug,eth \
    --authrpc.jwtsecret /tmp/jwt.hex \
    -d

5. Replay payloads

bash

bench send-blocks \
    --engine http://localhost:8551 \
    --jwt-secret /tmp/jwt.hex \
    --input /tmp/big-blocks.ndjson \
    --wait-for-persistence every:2 \
    --report json:/tmp/reth-bb-report.json

bench send-blocks submits each payload through reth's custom reth_newPayload and reth_forkchoiceUpdated Engine API methods.