What is the Parallel EVM?

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INTRODUCTION

Parallel Ethereum Virtual Machines (EVMs) are a new, alternative basis for building layer-1 blockchains as compared to the standard EVM that powers the Ethereum network. This article will describe the original EVM, look at how the Parallel EVM builds upon this, and discuss some of the leading parallel EVM blockchains. 

Ethereum is the largest smart contract blockchain network, home to over 60% of the total-value-locked (TVL) in DeFi, and home to some of the biggest DeFi applications including Aave, MakerDAO, Synthetix, and others. However, as with any network that facilitates communication and value transfer, ensuring scalability is a crucial task for the long-term success of the network and its ecosystem. As new networks are constantly emerging in the public blockchain landscape, so are new designs and mechanisms for enabling faster, cheaper, and more efficient blockchain networks. The Parallel EVM is one such approach to achieving better scalability.

UNDERSTANDING THE ETHEREUM VIRTUAL MACHINE

The Ethereum Virtual Machine, or the EVM, is the software environment for the Ethereum network, in which transactions are processed and executed.

WHAT IS A VIRTUAL MACHINE?

A virtual machine, or VM, is a software program which creates a newly simulated, software-based computer system within a physical computer, which expands the functionality of the underlying computer. VMs enable people to do something on their computer that they otherwise couldn’t. 

For example, VMs allow you to play an old video game from the 90s on your computer or smartphone today. By default, this is not possible as the particular hardware requirements needed for running the game are not available on your current device, as they’re built for a device from that era. A virtual machine replicates all of the necessary requirements for running that video game, allowing you to play the game on your modern device. 

VIRTUAL MACHINES AND BLOCKCHAINS 

This concept can then be applied to blockchains as well. Blockchains are distributed networks that facilitate transfer of value and communication between different parties without a centralized intermediary to approve or disapprove any particular transaction. Instead, transactions are validated by a decentralized network of computers communicating with each other to record new valid transactions. Blockchain virtual machines are the software, or execution environment, these node operators use to communicate and validate transactions.

THE ETHEREUM VIRTUAL MACHINE

The Ethereum Virtual Machine, or the EVM, is the execution environment for the Ethereum network. It is the environment in which smart contracts interact with one another, and transactions are processed and executed. It is like the server allowing all Ethereum nodes across the globe to play the multiplayer Ethereum game in real-time. 

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Today, transactions are processed in sequential order, that is one at a time, on Ethereum due to the design of the EVM.

A transaction on Ethereum roughly goes through the following flow:

1. User submits a signed transaction from their wallet. 
2. The pending transaction lands in the public mempool, akin to a waiting room for blockchains. 
3. A block proposer (a type of validator) then picks up the transaction along with a handful of others, and “proposes” them to be added to the next block. 
4. Other validators oversee and “validate” the contents of the transactions, and upon approval, the transactions are then added collectively to a block that is added to the network. Our transaction is confirmed! 
5. The EVM executes the transactions within a block one by one, after which the transaction is complete and our recipient receives their funds. 
   

Adding transactions sequentially ensures that each new transaction is valid and compatible with all previous transactions.

However, sequential processing creates a bottleneck when network activity increases and more transactions are fighting to be included in the next block. This leads to longer wait times for users, higher gas fees, and an overall unpleasant user experience. Parallel processing is meant to solve these problems.

WHAT IS PARALLEL PROCESSING?

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Pioneered by Solana, parallel processing for blockchain transactions brings significant improvements to the blockchain’s throughput and execution speed. These high-performance blockchains aim to process transactions in milliseconds. But how exactly is this possible? 

The concept of parallel processing for blockchains can be distilled into the idea that non-conflicting transactions should be able to be processed and executed simultaneously. If Bob wants to make a swap, Alice wants to mint a new NFT, and Eric wants to stake his funds with a validator, all transactions can be processed at once rather than sequentially, reducing transaction processing time and cost to create a better experience for Bob, Alice, and Eric.

Parallel processing in blockchains was pioneered by Solana. Solana’s Sealevel engine allows multiple smart contracts to run simultaneously due to a unique feature in the Solana Virtual Machine (SVM) design which requires smart contracts to declare which part of the network, or state, they need to access to execute a transaction. This design has enabled Solana to deliver over 2,000 transactions per second (TPS) and block confirmation times of 400ms. 

DEMYSTIFYING THE PARALLEL EVM

The problem is that the Solana Virtual Machine is not compatible with the Ethereum Virtual Machine, meaning anyone migrating their dApps over from Ethereum needs to start from the ground up and build in another programming language. 

What if there was a way to bring the performance of parallel processing to an EVM-compatible blockchain? Enter the Parallel EVM.

A Parallel EVM is an execution environment for blockchains that aims to bring the best of both worlds from the Solana and Ethereum blockchains’ designs - parallel transaction processing that is compatible with the Ethereum Virtual Machine.

There is no single predominant Parallel EVM. Instead, a number of teams have been working on building their own implementations, united by the common goal of bringing the speed and efficiency of Solana to the Ethereum ecosystem. 

THE PARALLEL EVM ECOSYSTEM

NEON

Neon was the first parallel EVM, launching in late 2022. Neon is an execution environment which exists as a smart contract on Solana, allowing smart contracts and programs on Ethereum to access the technical benefits of Solana. Neon processes new blocks in 0.4 seconds on average. Neon is still very small, with only $1.2M in TVL and 6 apps.

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SEI

Sei Network is a parallel EVM Layer 1 blockchain that uses optimistic parallel processing, which means transactions are processed quickly based on optimistic assumptions, and can be disputed later on if proven to be false. Built with trading and financial applications in mind, Sei has an average block time of 0.46 seconds and is home to over 80 applications.

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MONAD

Similar to Sei, Monad uses optimistic parallel processing to enable faster performance and speed, but it also introduces “superscalar pipelining”, a design used in computer systems which divides tasks into smaller tasks that get executed simultaneously. Monad claims to deliver up to 10,000 TPS with 1 second block confirmations and 1 second block finality, though the network is currently in closed testnet, therefore performance statistics are not yet widely available. 

POTENTIAL PROBLEMS WITH PARALLEL EVMs

Validation Errors: Speed and performance can trade off against accuracy.. Optimistic processing means the network assumes that submitted transactions are valid, and can investigate and roll back transactions afterward if needed. Though there haven’t been any major reported issues yet, the implications of enabling this on a larger scale are still unclear.

Network Centralization: Optimizing for speed also means there are greater hardware requirements for participating as a validator for the network, which can exclude a greater number of people and benefit a select few entities. This has been one of the common criticisms of Solana, and Parallel EVM blockchains will likely face similar criticisms. 

CONCLUSION

The Parallel EVM represents a culmination of learnings from the Ethereum and Solana blockchains, and aims to provide the familiarity of the traditional EVM experience, with the processing power of a parallelized blockchain like Solana. It’s a novel approach to scaling blockchains being pioneered by teams like Sei, Monad and Neon. It presents an alternative approach to Ethereum scaling as compared with traditional Layer-2 solutions, rollups & sidechains.