Sui Lutris: Analysis of the Core Distributed System Protocol of the Sui Public Chain

Recently, Mysten Labs released a technical report on Sui Lutris, a distributed system that supports Sui. This system allows Sui to maintain low latency under conditions of high throughput and long-term stability.

After months of testing, Mysten Labs updated the Sui Lutris white paper on August 18, confirming the following key points:

1. By using parallel transaction blocks (PTBs) and a configuration of 5000 TPS, Sui can process 140,000 to 150,000 operations per second, which far exceeds its mainnet peak performance (approximately 700 TPS).

2. Even in the case where some verification nodes stop operating, Sui's final confirmation delay can still be maintained below 0.5 seconds.

The white paper also details the operational mechanism of Sui and provides security proofs along with guidance on how external testers can reproduce relevant data in their own verification tests.

Since the advent of Bitcoin, blockchain technology has made significant progress, with emerging applications such as games and NFTs constantly emerging. The blockchain community continues to explore ways to improve efficiency, with a particular focus on high-load processing and real-time latency optimization.

Currently, L1 blockchains face two main challenges: achieving high throughput while maintaining low latency, and ensuring the long-term stability of the consensus protocol. These challenges can be addressed through the dynamic participation and configuration of validating nodes.

An effective way to achieve high throughput is to adopt DAG-based consensus protocols, such as Narwhal/Bullshark used by Sui. These protocols can execute a large number of transactions simultaneously, making them very suitable for application scenarios such as games and NFTs. However, DAG-based protocols often lead to a delay of several seconds, which can significantly impact certain common operations.

On the other hand, non-consensus protocols demonstrate great potential in reducing latency and scaling, as shown by the previously studied FastPay prototype. These protocols achieve fast transaction processing by eliminating the consensus step. However, they are only applicable to a limited category of simple blockchain operations, which restricts the expressiveness of smart contracts, and they face challenges in dynamically adjusting the set of validating nodes.

Sui Lutris, as the core protocol of the Sui network, innovatively combines DAG-based consensus and consensus-less methods, achieving the advantages of both: sub-second latency and a sustained throughput of thousands of transactions per second. At the same time, Sui retains the ability to execute complex contracts on shared objects, generate checkpoints, and reconfigure the set of validating nodes across cycles.

The innovative approach of Sui Lutris

Sui Lutris adopts a unique hybrid approach. For operations on single-owner assets (unique objects), the system uses a consistent broadcasting protocol among verification nodes to achieve latency below consensus. For complex smart contracts on shared objects, Sui Lutris relies solely on the consensus mechanism. Additionally, it supports network maintenance operations such as defining checkpoints and reconfiguring verification nodes. This innovative strategy provides a balanced transaction processing solution in complex Byzantine environments.

The transaction lifecycle of Sui Lutris includes the following steps:

1. The user creates and signs the transaction.
2. Transactions are sent from the full node to the validating node for verification and signing.
3. The client collects the responses from most validation nodes to form a transaction certificate.
4. The certificate is sent back to the verification node for confirmation. Unique object transactions can be executed immediately, while other transactions are forwarded to the consensus protocol.
5. Consensus output certificate number, verification node executes shared object transaction.
6. The client collects the responses from the validation nodes as proof of transaction settlement.
7. Form checkpoints for each consensus submission to drive the reconfiguration protocol.

In addition to the main trading process, Sui Lutris also provides multiple support features:

• The checkpoint protocol records all transaction history for easier auditing and synchronization.
• Support reconfiguration at the end of each cycle to adjust the validator set and their voting power.
• Safely "unlock" mistakenly locked assets at the end of the cycle to minimize potential losses.

As the infrastructure of Sui, the complete technical report of Sui Lutris provides more details about the security and activity protocol, as well as the security proofs in the standard distributed system model.