What is Parallel EVM?

In blockchain technology, the quest for scalability, speed, and efficiency drives innovation. Ethereum stands as a colossus, continually pushing the boundaries of what is possible. At the heart of this relentless drive lies the Ethereum Virtual Machine (EVM) – the powerful engine (a runtime environment) that executes the smart contracts forming the backbone of Ethereum and other EVM based blockchains’ decentralized applications. However, as the network grows and the demand for decentralized applications skyrockets, the EVM faces a formidable challenge: scaling to meet the needs of millions of users worldwide.

What is Runtime Environment?

Before we dive into the heart of the subject matter, we should note that the “runtime environment” is crucial for abstracting the complexities of hardware and operating system interactions away from developers, allowing them to focus on writing code that is portable and easier to manage. It also plays a significant role in ensuring the security and efficiency of program execution, by managing resources and isolating execution processes to prevent unwanted interactions between applications. Now let’s see what exactly EVM is.

What is EVM in Blockchain?

Let’s take the concepts mentioned in the above para and apply to blockchain technology, and more specifically, the largest smart contract platform – Ethereum. The EVM abstracts the complexities of the underlying hardware and operating system from developers, allowing them to focus on writing smart contracts in high-level programming languages like Solidity. A smart contract is a self-executing contract with the terms of the agreement between parties directly written into lines of code, deployed and run on a blockchain network. With the EVM abstraction, smart contracts are easily managed and ported across the Ethereum network, irrespective of the underlying system architecture.

The EVM plays a critical role in ensuring the security and efficiency of smart contract execution. It isolates each smart contract, running them in a virtualized environment to prevent unwanted interactions that could lead to vulnerabilities or exploits. This isolation also ensures that a faulty or malicious contract does not affect the operation of others or the Ethereum network as a whole.

Additionally, the EVM manages computational resources through the concept of gas (akin to transaction costs), which is paid by users to execute operations on the Ethereum network. This mechanism helps to prevent resource abuse by making it costly to execute operations that would overload the network, thereby enhancing the efficiency and stability of Ethereum.

EVM Compatibility Across Independent Blockchains

Standalone blockchains including layer 1’s opt for EVM compatibility mainly to leverage the extensive ecosystem of Ethereum, including its tools, dApps, and developer community. EVM compatibility allows these blockchains to execute Ethereum-based smart contracts without much modification, facilitating interoperability within the blockchain space. This compatibility is crucial for attracting developers already familiar with Ethereum’s development environment and for ensuring that existing applications can easily migrate or extend their reach beyond Ethereum itself.

By undertaking EVM parallelization, various EVM compatible blockchain networks, aside from Ethereum, can improve its transaction throughput and smart contract execution efficiency, making it more competitive and attractive to users and developers alike. And in a nutshell, that’s the answer to the question you may have in your mind – why do we need Parallel EVM in the first place? Let’s see how exactly Parallel EVM helps to optimize smart contract platforms’ performances. And whether it is enough to solve the seemingly endless scalability issues blockchain networks face?

What is Parallel EVM?

Parallel EVM is a groundbreaking approach that promises to catapult Ethereum ecosystem’s (that includes layer 2’s building on Ethereum, standalone layer 1 networks, DeFi protocols and other dApps) performance into a new era. By breaking down the monolithic process of transaction execution into parallel strands, EVM parallelization aims to harness the full potential of modern computing hardware, making the dream of real-time, gas-efficient, and scalable blockchain applications a reality. This blog will embark on a journey through the complex, yet fascinating world of Parallel EVM, exploring its mechanisms, challenges, and the impact it holds for the future of the blockchain industry. 

Parallelization within the Ethereum Virtual Machine (EVM) allows for the concurrent execution of multiple transactions, moving away from the traditional approach of executing transactions sequentially. This approach is akin to delegating tasks among a larger team, aiming to reduce the time required for completion and boost overall efficiency. But we have to keep the following in mind – spreading the work in the context of Parallel EVM doesn’t necessarily mean distributing it across more nodes in the blockchain network. Instead, it primarily refers to utilizing the computational resources of a single node more efficiently by executing multiple transactions or operations in parallel. This could involve leveraging techniques like multiple cores or processors within individual nodes (server or computer) to handle different tasks concurrently. Scaling solutions (both on-chain and off-chain), and redesigning certain aspects of the blockchain’s architecture are also other techniques to enable parallel processing.

How Parallel EVM Affects Scalability

Vertical Scalability

Most blockchain networks today scale vertically as opposed to horizontally i.e. by upgrading the existing infrastructure to make it more powerful such as increasing CPU power, RAM, or storage. In the context of a blockchain node, this could mean using more powerful hardware to process transactions faster. Now when the load on the network peaks, the throughput (or TPS) limit gets throttled resulting in traffic congestion, slow processing and increased gas fees (as a result of increased demand). This can especially happen in networks that are designed in a way where individual nodes store the complete history or significant part of its ledger for redundancy. Consequently, these nodes may become less efficient directly leading to increased transaction/network latency, which, in turn, leads to congestion, elevated gas fees and poor user experience.

Parallel EVM directly impacts vertical scalability. By leveraging techniques such as multiple cores or processors within a single node, a Parallel EVM makes individual nodes more efficient at processing transactions. This doesn’t significantly increase the number of transactions the network as a whole can handle at once or the level of decentralization, but it does mean that each node can handle its transactions more quickly and efficiently. For networks where node performance is a bottleneck, this can significantly improve overall performance and throughput.

Horizontal Scalability

Networks like Shardeum are innovating in this space by scaling horizontally i.e. by adding more individual nodes to the network to handle increased load and maintain data integrity. The impact of parallel EVM execution on linear scalability is less direct but still significant. Since Parallel EVM improves the efficiency of individual nodes, more efficient nodes can lead to a more robust and responsive network, as each node can handle its share of the workload more effectively. This means that as the network scales linearly or horizontally, the improved efficiency of each node allows the network to maintain or even improve its performance per node (TPS per node), leading to better overall network health and scalability. 

If a network comprises 5,000 nodes, each capable of processing one transaction per second (1 TPS per node), then collectively, the network could achieve a throughput of 5,000 TPS. This stands in stark contrast to the average throughput of 100 TPS that is typical for current public blockchains, even with thousands of nodes. With the implementation of Parallel EVM, the processing capability of each node on a horizontally scalable network could be enhanced beyond the baseline TPS, potentially elevating the overall network throughput. 

How Are Standard EVM and Parallel EVM Different?

Good question. As indicated previously, the traditional Ethereum Virtual Machine operates on a sequential processing model, which is good and organized enough during low transactional demands. However, as transaction volumes surge — a common scenario for bustling blockchains like Ethereum and others — this sequential approach becomes a bottleneck, giving rise to congestion and inefficiencies. Extended processing times not only frustrate users but also escalate costs.

Parallel EVM introduces the capability for the Ethereum Virtual Machine to process multiple transactions and smart contract operations parallelly. This parallel execution approach significantly increases the amount of work completed at the same time, enhancing a network’s scalability. Such scalability improvements are achievable particularly when the operations within each Parallel EVM are independent and do not rely on the results of others.

How Does Parallel EVM Work?

Let’s consider this scenario where you’re sending digital token gifts to three friends: Zaira, Victor, and Taylor. 

In a traditional EVM setup, the node responsible for processing your transactions would handle them sequentially. This means the node picks up the transaction for Zaira, processes it, confirms it, and only then moves on to Victor’ transaction, followed by Taylor’s. If the node is dealing with a high volume of transactions across the network, this sequential processing can slow down the confirmation times or finality, not just for your transactions but for everyone else’s.

Now, imagine this node is equipped with Parallel EVM capabilities. The key difference here is that this node can now analyze the transactions you’ve initiated, through various techniques like multiple cores and advanced algorithms, and recognize that they are independent of one another—none of the token transfers interfere with or rely on the others for their execution.

The node, leveraging Parallel EVM, processes the transactions to Zaira, Victor, and Taylor simultaneously. Since these are simple, non-interfering token transfers, they can be handled in parallel without any risk of incorrect ledger updates or conflicts. And by processing these transactions concurrently, the node significantly cuts down on the total processing time. This efficiency gain means that all your three friends receive their gifts much quicker. Furthermore, this enables the node to quickly proceed to processing additional transactions in the queue. When every node across the network is equipped with Parallel EVM, a transformative effect occurs, markedly elevating the system’s total throughput and performance. Eventually, this would potentially lead to better user experience and lower gas costs.

How Can We Implement Parallel EVM?

The feasibility and timeline for implementing Parallel EVM across Ethereum and other EVM compatible chains hinge significantly on the progress and intensity of research and development efforts in this domain. Given that the concept of Parallel EVM was proposed relatively recently, its realization into practical, scalable solutions will be shaped by ongoing innovations and explorations within the blockchain technology community. However, here are some plausible methods that are being actively explored:

1. Advanced Algorithms

Utilizing advanced algorithms, the EVM analyzes the bytecode of smart contracts to determine the read and write operations to the state. If two transactions access different parts of the state or if their accesses do not conflict, they are marked as parallelizable.

2. Sharding and Cross-Shard Communication Protocols

The EVM state can be divided into manageable shards or partitions, each capable of being processed independently. Transactions affecting different shards can be processed in parallel by the same node. Cross-shard communication mechanisms would be crucial for maintaining the blockchain’s integrity and consistency. Numerous sharded blockchains, including MultiversX, Near, and Shardeum, employ sharding at the protocol level to achieve enhanced scalability and maintain decentralization across their networks. This foundational approach to sharding paves the path for parallelizing the EVM state utilized within their smart contract platforms.

3. Transactional Memory Systems

Developers can implement software or hardware transactional memory (STM or HTM) systems within the EVM to manage concurrent accesses to the blockchain state. Here, transactions are executed in a speculative manner, with the system keeping track of all changes. If no conflicts are detected at commit time, the changes are made permanent. In case of conflicts, the transaction may be rolled back and retried, ensuring that parallel executions do not result in inconsistent states.

4. Virtualizing EVM Execution Layer

Developers can create isolated execution environments within the EVM that can run in parallel, each handling a subset of transactions from a block. Similar to process threading in operating systems, this method would involve virtualizing the EVM execution layer to allow multiple threads or processes to run side-by-side, isolated from each other but under a controlled, overarching management system to ensure consistency and synchronicity when needed.

Parallel EVM Challenges

Let’s now look at some of the challenges pertaining to Parallel EVM implementation to improve the efficiency and scalability of the Ethereum ecosystem:

• Parallel EVM is still in an experimental phase so we will have to wait for wider adoption and see how it performs.
• The practical implementation, especially for interconnected transactions, involves carefully managing dependencies and conflicts to maintain the correctness and integrity of blockchain state
• Parallel EVMs are not easy to either integrate into a network or maintain. The unique design requirements call for many rounds of testing
• Any changes to how transactions are processed, including parallel execution, must be carefully analyzed for security implications, ensuring that they do not introduce vulnerabilities.
• Leveraging parallel EVM might require nodes to upgrade their hardware and software, which could impact the decentralization aspect if only nodes with higher-end resources can efficiently participate in the network
• Improvements in node efficiency must still work within the constraints of the blockchain’s consensus mechanism. Faster transaction processing must be reconciled with the pace at which the network can reach consensus.

Future Implications and Research Directions

In the immediate future, developers would have to work on ensuring seamless integration with existing systems and little to no conflicts when it comes to interdependent transactions. In the long run, parallel EVMs may boost cross-chain communications and the operational efficiency of standalone blockchain networks. As more and more networks add the Parallel EVM technology to their systems, we will gradually find out how effective the tech proves to be. 

However, here’s the disclaimer which experts agree in general. While Parallel EVM can enhance transaction processing capabilities, it alone cannot address the broader challenge known as the blockchain or scalability trilemma. This trilemma underscores a fundamental constraint: at any given time, a blockchain network struggles to simultaneously achieve high levels of security, decentralization, and scalability. Overcoming this trilemma is often seen as the ultimate achievement for blockchain systems, promising to eliminate issues of operational inefficiency and elevated transaction costs.

To truly resolve this issue, it requires a comprehensive and foundational approach from distributed system researchers. The design of blockchain protocols—or the base layer—must be rethought from the ground up. This involves integrating key architectural components optimally, including the consensus algorithm, transaction processing mechanisms, atomic composability, and fairness in transaction ordering, among other innovative solutions. Such a holistic strategy aims not just to incrementally improve performance but to fundamentally enhance the blockchain’s capacity to deliver on its promise of a secure, decentralized, and scalable technology utilized by masses.

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