Parallel Execution Is the Scalability Solution L2s Are Looking for, but Its Implementation Is Challenging

• Parallel execution boosts scalability by processing multiple transactions simultaneously, a key advantage showcased by Solana’s blockchain.
• Ethereum’s layer-2 solutions face challenges with parallel execution due to the EVM’s sequential design, which limits scalability.
• Achieving parallel execution without breaking EVM compatibility requires innovative solutions to balance performance and ecosystem integration.

One of the toughest challenges in blockchain design is still scalability, a problem the industry has been wrestling with for years. As more real-world applications move on-chain, finding a solution is becoming increasingly urgent.

Solana, often regarded as Ethereum’s top competitor, has been making headlines in the crypto space. With its impressive transaction speeds and growing developer community, it’s easy to see why.

One of the key reasons for Solana’s success is its ability to process transactions in parallel, meaning it can handle multiple transactions simultaneously. This drastically boosts scalability and lowers transaction costs, making it a go-to choice for developers and users.

For Ethereum’s layer-2 (L2) solutions to keep up with Solana, they’ll need to achieve similar transaction-processing capabilities, which means adopting parallel execution. But here’s the big question:

If parallel execution is crucial for scalability and staying competitive, why is it so hard for L2s to implement?

What Is Parallel Execution and Why Is It Crucial?

Modern devices are built with multiple processors, allowing them to handle different tasks simultaneously. Take smartphones, for instance. Their multi-core processors make multitasking smooth and efficient.

This same technology powers supercomputers to process massive amounts of data at incredible speeds.

In simple terms, parallel execution  uses multi-core processors to process multiple transactions simultaneously, making the most of today’s powerful hardware.

In blockchain, scalability becomes as straightforward as adding more hardware, which is relatively affordable.

Solana has mastered parallel execution, giving it a big advantage over Ethereum’s ecosystem, where implementing this kind of technology is still a tough nut to crack.

Ideally, if you have 100 processor cores, you could theoretically scale up performance by 100 times. In reality, because of practical limits like Amdahl’s Law, the improvement is closer to 50x.

Even so, 50x is a huge leap forward and highlights why parallel execution is a game-changer for blockchain scalability.

Parallel Execution Is Promising but Challenging

Parallel execution has enormous potential, but it comes with its own set of challenges. Most layer-2 solutions aim to stay fully compatible with Ethereum’s layer 1, which means sticking to Ethereum’s original architecture designed to process transactions one at a time.

Ethereum Virtual Machine (EVM) follows a simple, step-by-step process: It takes a transaction, processes it, writes the results to the database, and only then moves on to the next one. This sequential design keeps things straightforward but limits scalability.

Parallel processing takes a different approach by handling multiple transactions simultaneously, which can significantly boost throughput. It allows for much more efficient use of resources and faster processing times. Still, it’s not without complications.

Designing a system that can process tasks in parallel without errors or conflicts is a complex challenge. It requires careful planning to ensure reliability, consistency, and smooth operation across the entire network.

Performance vs. EVM Equivalence

Most layer-2 solutions have chosen to inherit Ethereum’s EVM design to maintain EVM equivalence . However, the EVM doesn’t support parallel execution.

Adding parallel execution to the EVM would require significant changes to its current architecture. These changes could break EVM equivalence, meaning applications running on Ethereum might no longer be compatible, a critical factor for adoption and ecosystem growth.

In addition, execution is just one part of the system that requires optimization.

Other key modules, such as data storage, state management, and network communication, must also handle the increased workload generated by parallel execution to maintain overall system performance and scalability.

If these supporting modules cannot keep up, the benefits of parallel execution are pretty limited.

Scalability Will Require Innovative Solutions

Parallel execution is key to scaling blockchains, just like in many other areas of computer science. Still, adding parallel execution to the EVM isn’t straightforward because it wasn’t designed with that in mind.

Making parallel execution work while keeping full EVM compatibility is a difficult challenge that will require clever thinking and innovative solutions to ensure the system remains functional and fully integrated with the broader Ethereum ecosystem.