Aptos makes Block-STM v2 its default parallel execution engine

Aptos has switched its blockchain to a new default engine for processing transactions. Block-STM v2, the upgraded version of the network’s parallel execution system, now runs by default on the Layer-1 chain. Most users will never notice the change. That is sort of the point: the upgrade happens under the hood, and neither users nor decentralized applications need to do anything. How Block-STM v2 works The technical term for this is optimistic concurrency control. The engine executes transactions speculatively across multiple processor threads at the same time. It then checks each transaction’s read and write sets, meaning the data it looked at and the data it changed. Those sets are validated against an ordering that consensus has already fixed in advance. When two transactions conflict, only those specific transactions are re-executed. The final result is deterministic and serial-equivalent. One feature stands out for developers. The v2 engine handles parallel execution dynamically, without requiring upfront access lists or dependency declarations. The numbers behind the upgrade The original Block-STM already set a high bar. In 2022 benchmarks, v1 hit roughly 170k transactions per...