Ethereum developers recently held their 107th All Core Developers Consensus (ACDC) call on April 20, 2023, where they discussed and coordinated changes to the consensus layer (CL) of Ethereum. They provided updates on their progress around Deneb and discussed what other code changes in addition to Ethereum Improvement Proposal (EIP) 4844 should be included in Ethereum’s next upgrade.
Following the successful activation of Shanghai last week on April 12, Ethereum developers immediately switched their focus on preparations for Cancun. Cancun is the name of the next upgrade on the execution layer (EL) of Ethereum, while Deneb is the corresponding upgrade name for the CL. During ACDC call 159, developers began discussing the final scope of the Cancun/Deneb upgrade centered around EIP 4844, the implementation of blob transaction types. After acknowledging the success of Shanghai, developers then discussed preparations for Deneb, starting with the launch of devnet #5.
Developers have been launching multi-client test networks, also called devnets, for EIP 4844 since as early as October. The fifth devnet for EIP 4844 will be launched next week. The Chair of the ACDE calls, Tim Beiko, said that Paritosh Jayanthi, a DevOps Engineer for the Ethereum Foundation, is in the process of doing trial runs for clients like Ethereum JS (EL) and Lodestar (CL) to prepare them for the devnet launch next week.
There is a minor change to the Engine API that merges the “getPayloadV3” and “getBlobsBundleV1” calls into one. Although this change has not yet been merged into specifications for EIP 4844 on GitHub, it will be in the next few days so that the change can be live for testing on devnet #5. Beiko urged client teams to review the change as soon as possible.
Developers also discussed concerns around how blob transactions should be reinserted into blocks in the event of a chain reorganization. This issue was raised by Geth (EL) developer Péter Szilágyi during a presentation he gave at ETHTokyo. Due to the decoupled nature of blob transactions from regular transactions, reconstructions of blobs after a chain reorg may only be available from transactions seen in the public mempool. Given that there are plenty of transactions that bypass the mempool, such as MEV transactions and bundles, one way to guarantee all blobs can be reconstructed, including those that bypass the mempool, is to have the CL pass along blob data for every block to the EL.
Alternatively, the network could require users who have submitted transactions bypassing the mempool to resubmit their transactions in the event of a chain reorg. Szilágyi recommended that the former solution should be implemented, where the blob data is communicated to the EL, so that in the event of a reorg, transactions can be reinserted, even those that bypass the mempool. Ryan, however, expressed his concern that this proposed solution would further break down the abstraction between the EL and CL layers, and reinforce the assumption that nodes will store full copies of blob data.
Szilágyi also talked about the implementation of data availability sampling (DAS), where he said that there would be other expectations around data availability that would have to change for this upgrade. He recommended that developers “try to cross that bridge once we get there.” Ryan agreed and asked what other developers thought around the edge case of chain reorgs and blob transaction reinsertions. Gajinder Singh, a developer for the Lodestar (CL) client, said that since MEV transactions are the most common type that bypass the public
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