Analyzing Empty Block Production in Bitcoin Mining Pools

In the world of Bitcoin mining, the production of empty blocks—blocks that contain only the coinbase transaction rewarding the miner—has been a topic of discussion and analysis. This article examines data on the proportion of empty blocks produced by various mining pools over time, explores the strategies that may influence these rates, and discusses the implications for network performance and security.

What Are Empty Blocks?

Empty blocks are Bitcoin blocks that do not include any transactions besides the mandatory coinbase transaction. They occur when miners create and submit a new block without adding any transactional data. While sometimes viewed as inefficient, empty blocks can result from legitimate mining strategies or technical constraints.

Historical Data on Empty Block Rates

The following analysis presents data collected from several major mining pools between 2014 and 2017. The figures illustrate the percentage of empty blocks produced by each pool during different periods.

2017 Data (Through October 22)

2016 Data

2015 Data

Why Do Miners Produce Empty Blocks?

Simplified Payment Verification (SPV) Mining

Miners often aim to build new blocks as quickly as possible to extend the blockchain and maximize profits. To do this, they may start mining a new block before fully downloading and validating the previous one. Since they are unaware of which transactions were included in the prior block, they often avoid adding any transactions to avoid double-spending and orphaned blocks. This practice is known as SPV mining.

Supporters argue that SPV mining is a legitimate profit-maximizing strategy. Critics, however, claim it reduces network efficiency by leaving block space unused and may increase the risk of transaction reversals.

SPY Mining

Another related concept is SPY mining. In this approach, a miner participates in a pool not to contribute hashing power but to "spy" on other miners. The goal is to quickly obtain the hash of the previous block and use that information to gain a competitive advantage.

Pool Policies

Different mining pools adopt varying policies regarding empty blocks. For example, Bitfury has historically produced almost no empty blocks, while Antpool has shown higher rates. These differences are often attributed to varying approaches to SPV mining.

The ASICBOOST Allegation

Some analysts have suggested that a higher empty block rate could indicate the use of covert ASICBOOST—a mining optimization technique that allows for more efficient hashing. Proponents of this theory point to the following:

• Antpool consistently showed high empty block rates until April 2017.
• In April 2017, BTC.com (owned by the same company as Antpool) began showing similarly high rates.
• In October 2017, an unknown miner emerged with high empty block production, possibly suggesting an attempt to obscure mining strategies.

While these patterns are interesting, they are not conclusive evidence. Further research is needed to validate these claims.

The Impact of Block Time Intervals

The time between blocks also influences empty block production. If a miner finds a new block within 30 seconds of the previous one, they may not have had time to validate transactions, leading to an empty block. When excluding blocks found within 30 seconds of the previous one, the empty block rate decreases significantly—supporting the idea that SPV mining is a key factor.

Small vs. Empty Blocks

It's worth noting that not all small blocks are empty. Some blocks contain few transactions, which could also be related to mining strategies like ASICBOOST. Comparing Antpool and Bitfury data shows that Antpool produces more small blocks regardless of the time since the last block, while Bitfury does so only when the time interval is short.

This irony is notable: some pools that advocate for larger blocks actually produce more small blocks in practice.

Frequently Asked Questions

What is an empty block?
An empty block is a Bitcoin block that contains no transactions other than the coinbase transaction. Miners may produce them due to technical constraints or strategic choices.

Why do mining pools produce empty blocks?
Pools may produce empty blocks when they haven’t yet validated the previous block’s transactions. This practice, known as SPV mining, helps them quickly extend the blockchain and secure rewards.

Do empty blocks harm the Bitcoin network?
While empty blocks do not directly harm security, they reduce the network’s transaction throughput and efficiency. Critics argue they increase the risk of double-spending and reduce reliability.

What is ASICBOOST, and how does it relate to empty blocks?
ASICBOOST is a technique to increase mining efficiency. Some believe that producing empty or small blocks can facilitate covert ASICBOOST, though this remains a speculative theory.

How can I monitor empty block production?
👉 Explore real-time blockchain analytics tools for up-to-date statistics on block sizes and mining pool activities.

Are there solutions to reduce empty blocks?
Improvements in network propagation and validation efficiency can help. Additionally, miners can adopt policies that prioritize transaction inclusion without significantly delaying block production.

Conclusion

Empty block production is a complex phenomenon influenced by technical and economic factors. While data shows significant variation among pools, attributing these differences solely to strategies like SPV mining or ASICBOOST remains speculative. Understanding these patterns requires continued observation and analysis.

As the Bitcoin network evolves, miners, developers, and users must collaborate to balance efficiency, security, and profitability. Transparent data and robust analytics are essential for informed decision-making.