Read-copy-update reorganized synchronization around cheap readers, versioned updates, and delayed reclamation, making read-mostly kernel data structures scale without conventional reader locking.
Mercurial emerged in 2005 alongside Git as a fast distributed version-control system for large projects, emphasizing a compact command model and scalable cloned histories.
Linux kernel development scaled through public mailing lists and a distributed maintainer network that routes patches through trusted subsystem experts rather than a single central engineering hierarchy.