threadsvirtualization

Threads virtualization is a software abstraction that allows application concurrency to be expressed as a large number of virtual threads, which are scheduled and executed on a smaller set of physical resources. Virtual threads usually have independent stacks and state, but are multiplexed onto real CPU threads by a runtime, library, or hypervisor.

Implementation typically falls into several categories. User-level threading libraries implement green or user-space threads scheduled in software and mapped onto kernel threads. Language runtimes may provide native virtual threads or fibers with lightweight contexts and fast switching. In other models, kernel or hypervisor facilities multiplex virtual threads across a pool of kernel threads to improve isolation and resource management.

Benefits include improved scalability for high-concurrency workloads, reduced per-thread memory and context-switch costs, and the ability to express asynchronous workflows with a familiar threading model. Virtual threads are used in web servers, event-driven services, and runtimes that manage many concurrent tasks. Performance is workload-dependent, and virtualization can introduce new overheads in some scenarios.

Challenges include debugging complexity, potential scheduling unfairness, and increased memory use due to per-thread stacks. Integrating with existing OS I/O, security, and resource accounting models may require careful design. Portability across languages and platforms is another consideration.

Related concepts include green threads, fibers, coroutines, thread pools, asynchronous I/O, and language-specific implementations such as Java virtual threads and Go's goroutines.