The Ethereum blockchain just launched its first-ever shadow fork, a type of underlying change in the network’s protocol on a mainnet or testnet.
What's a shadow fork, and what does this mean for the Ethereum network amid its transition to a proof-of-stake consensus mechanism?
Ethereum’s shadow fork goes live
On April 11, Ethereum launched its first shadow fork on the mainnet blockchain. According to Ethereum Foundation developer Parithosh Jayanthi, the shadow fork will help Ethereum “stress test our assumptions around syncing and state growth.”
Because the shadow fork operates alongside the existing mainnet, some Ethereum transactions may appear on both networks for the time being. The shadow fork processes one block per 14.8 seconds on average, according to a block explorer page.
To understand what a shadow fork is in crypto, you first need to understand what a fork is
A fork is any change to a network’s protocol. You may have heard of a hard fork, which is a significant change (like the Bitcoin Cash hard fork, which has 32-times larger block sizes than Bitcoin).
Meanwhile, a shadow fork is a change to the protocol that operates simultaneously and in partnership with the mainnet or testnet in question. In this case, the shadow fork is tied to the Ethereum mainnet. It’s used as a testing protocol that Ethereum can frequently debug and update to help further progress the mainnet. It “would dictate optimizations needed in the run up to the merge,” Jayanthi says.
Is Ethereum the first network to create a shadow fork?
Ethereum’s shadow fork is considered the first of its kind. The Ethereum Foundation developer who created the shadow fork, Marius van der Wijden, said in a tweet, “We're very close to a historical event. We're testing PoS on #Ethereum. Today will be the first mainnet shadow fork ever.” Given the decentralized and open-source nature of the larger cryptocurrency ecosystem, it wouldn’t be surprising to see other networks test their own shadow forks to help advance consensus technology as a whole.
To be clear, the shadow fork is a new technology. That’s why Jayanthi says about the Ethereum shadow fork, “To re-iterate, a shadow fork does not affect the canonical chain in any meaningful way. Since we reuse the chainID and the gossip channels are still connected, transactions submitted to the shadow fork could be included in the main chain as well. Proceed with extreme caution!”
What the shadow fork means for Ethereum’s progression to the "Consensus Layer"
Ethereum is in the process of a long-winded transition from proof-of-work (PoW) to proof-of-stake (PoS). These are types of consensus mechanisms that determine how a blockchain operates. PoW (what Bitcoin uses) is secure, but also more energy intensive than PoS. Bitcoin’s PoW is said to use 116.71 terawatt-hours per year for mining its native coin, BTC. Ethereum’s shadow fork is a part of the multistep transition to the Ethereum Consensus Layer, formerly known as Eth2.0.