The “Mass Exit” Issue in Rollups

Mo Ashouri
3 min readJul 10, 2023

When it comes to blockchain scaling solutions, rollups have become a popular option. They effectively increase the throughput of a blockchain by processing transactions off-chain and submitting only the final state to the main chain. However, as with any technology, they’re not without their potential issues. One such issue is what’s known as the “mass exit” problem. Let’s explore this issue in more detail here in this article.

What are Rollups?

We must first understand rollups to understand the “mass exit” problem. Rollups are a Layer-2 solution for blockchain scalability. Essentially, they allow for many transactions to be “rolled up” into a single transaction1. This means that instead of each individual transaction needing to be processed by the main chain, only the final state after several transactions are processed off-chain needs to be submitted. This dramatically increases the number of transactions that can be handled per unit of time2.

What is the “Mass Exit” Problem?

The “mass exit” problem arises when a large number of users simultaneously attempt to withdraw their funds from the rollup and move them back to the main chain3.

Let’s consider an example:

  1. Alice, Bob, and hundreds of other users are making transactions on a rollup.
  2. Suddenly, there’s a rumor of a critical vulnerability in the rollup’s smart contracts.
  3. Everyone (Alice, Bob, and others) tries to withdraw their funds back to the main chain all at once, fearing their assets might be at risk.

The problem lies here: The main chain (like Ethereum) has limited capacity. It can only handle a certain number of transactions within each block4. If too many people try to exit the rollup simultaneously, it could overload the main chain. This could result in a long waiting period for users to get their funds back, which can be especially problematic if the rollup does indeed have a serious issue.

How Can This Be Mitigated?

Various mechanisms can help to prevent or mitigate the “mass exit” problem:

  1. Fraud Proofs and Validity Proofs: These mechanisms ensure the state transitions within the rollup are valid5. Users can challenge invalid state transitions, which helps maintain the integrity of the rollup and reduces the likelihood of a mass exit.
  2. Well-Documented and Audited Code: As many mass exits may be prompted by fears of vulnerabilities, having thoroughly audited and transparent code for the rollup can help maintain user trust.
  3. User Education: By understanding the mechanisms in place to secure their transactions and the nature of rollups, users may be less likely to attempt a mass exit at the first sign of trouble.

I hope this article has helped you better understand the “mass exit” problem in rollups. If you have any further questions or topics you’d like me to cover, don’t hesitate to ask.

I’m Mohammadreza Ashouri, a Ph.D. in Cybersecurity and Blockchain. You can follow me for more insights and updates in this field.

Don’t hesitate to drop me your questions and follow for more content on cybersecurity and blockchain!

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Mo Ashouri

Mo has a Ph.D. in Compter Science. Mo specializes in Backend Programming and Security.