Understanding Two-Block Reorganizations in Bitcoin
The Bitcoin network recently encountered an unusual occurrence known as a two-block reorganization, often abbreviated as “reorg.” While this term can be alarming to those not well-versed in blockchain technology, it’s important to clarify that this event is not an indication of a network attack or a technical error. Instead, it reflects the intended operation of Bitcoin’s decentralized consensus system.
Multi-Block Rivalry Among Mining Pools
In this particular case, a noteworthy multi-block rivalry unfolded among prominent mining pools, specifically Foundry, AntPool, and ViaBTC. Data visualized by Bitcoin researcher b10c revealed that Foundry USA emerged victorious in this competitive scenario, successfully mining six consecutive blocks.
The network momentarily diverged into two distinct chains at block height 941880, wherein AntPool mined the subsequent block, 941881, while ViaBTC simultaneously produced block 941882 on the same chain. Competing against them, Foundry USA managed to generate its own version of block 941881, then continued its successful streak with block 941882.
Resolution of the Stalemate
This sequence resulted in a situation where the blockchain had two valid chains of the same length, a scenario that can lead to confusion. However, the stalemate was resolved when Foundry USA proceeded to mine additional blocks—941883, 941884, and 941885—consecutively. Consequently, the work completed by AntPool and ViaBTC was rendered obsolete, falling into the category of “stale” or “orphaned” blocks.
Conclusion
Overall, Foundry USA achieved an impressive feat by mining seven blocks in a row, from block 941879 to block 941885. While single-block reorganizations are a fairly common phenomenon within the Bitcoin blockchain, instances of two-block reorganizations are significantly less frequent, indicating that the temporary suspension between competing chains lasted through an entire block cycle.
