We received a bug report of a node restarting custody backfill unnecessarily after upgrading to Lighthouse v8.1.1. What happened is:
- User started LH v8.0.1 many months ago, CGC updated 0 -> N but the CGC was not eagerly persisted.
- LH experienced an unclean shutdown (not sure of what type).
- Upon restarting (still running v8.0.1), the custody context read from disk contains CGC=0: `DEBUG Loaded persisted custody context custody_context: CustodyContext { validator_custody_count: 0, ...`).
- CGC updates again to N, retriggering custody backfill: `DEBUG Validator count at head updated old_count: 0, new_count: N`.
- Custody backfill does a bunch of downloading for no gain: `DEBUG Imported historical data columns epoch: Epoch(428433), total_imported: 0`
- While custody backfill is running user updated to v8.1.1, and we see logs for the CGC=N being peristed upon clean shutdown, and then correctly read on startup with v8.1.1.
- Custody backfill keeps running and downloading due to the CGC change still being considered in progress.
- Call `persist_custody_context` inside the `register_validators` handler so that it is written to disk eagerly whenever it changes. The performance impact of this should be minimal as the amount of data is very small and this call can only happen at most ~128 times (once for each change) in the entire life of a beacon node.
- Call `persist_custody_context` inside `BeaconChainBuilder::build` so that changes caused by CLI flags are persisted (otherwise starting a node with `--semi-supernode` and no validators, then shutting it down uncleanly would cause use to forget the CGC).
These changes greatly reduce the timespan during which an unclean shutdown can create inconsistency. In the worst case, we only lose backfill progress that runs concurrently with the `register_validators` handler (should be extremely minimal, nigh impossible).
Co-Authored-By: Michael Sproul <michael@sigmaprime.io>
Lighthouse: Ethereum consensus client
An open-source Ethereum consensus client, written in Rust and maintained by Sigma Prime.
Overview
Lighthouse is:
- Ready for use on Ethereum consensus mainnet.
- Fully open-source, licensed under Apache 2.0.
- Security-focused. Fuzzing techniques have been continuously applied and several external security reviews have been performed.
- Built in Rust, a modern language providing unique safety guarantees and excellent performance (comparable to C++).
- Funded by various organisations, including Sigma Prime, the Ethereum Foundation, Consensys, the Decentralization Foundation and private individuals.
- Actively involved in the specification and security analysis of the Ethereum proof-of-stake consensus specification.
Staking Deposit Contract
The Lighthouse team acknowledges
0x00000000219ab540356cBB839Cbe05303d7705Fa
as the canonical staking deposit contract address.
Documentation
The Lighthouse Book contains information for users and developers.
The Lighthouse team maintains a blog at https://blog.sigmaprime.io/tag/lighthouse which contains periodic progress updates, roadmap insights and interesting findings.
Branches
Lighthouse maintains two permanent branches:
stable: Always points to the latest stable release.- This is ideal for most users.
unstable: Used for development, contains the latest PRs.- Developers should base their PRs on this branch.
Contributing
Lighthouse welcomes contributors.
If you are looking to contribute, please head to the Contributing section of the Lighthouse book.
Contact
The best place for discussion is the Lighthouse Discord server.
Sign up to the Lighthouse Development Updates mailing list for email notifications about releases, network status and other important information.
Encrypt sensitive messages using our PGP key.
Donations
Lighthouse is an open-source project and a public good. Funding public goods is hard and we're grateful for the donations we receive from the community via:
- Gitcoin Grants.
- Ethereum address:
0x25c4a76E7d118705e7Ea2e9b7d8C59930d8aCD3b(donation.sigmaprime.eth).
