Seathreads

Seathreads is a term used in computing to describe a conceptual grouping of threads that are bound to a particular user seat in a multi-seat environment. A seat is a collection of input and output devices (such as a display, keyboard, and pointer) that a user can use to interact with the system. Seathreads are intended to run with an execution context tied to that seat, enabling per-seat isolation of resources and input handling within a single operating system instance.

Rationale and design: The idea is to improve security, fault containment, and responsiveness on systems used by multiple users or devices. By associating threads with a specific seat, workloads on one seat can be kept separate from others, and resource usage can be accounted per seat. Scheduling and resource controls such as per-seat quotas or namespaces can be used to enforce isolation.

Implementation considerations: In practice, seathreads would build on existing mechanisms such as control groups (cgroups), Linux namespaces, and input/session management. A seat-aware scheduler and runqueue, along with per-seat IPC and file-descriptor namespaces, could help enforce isolation. The approach remains largely conceptual and is not a standardized feature across operating systems.

Applications and limitations: Seathreads are discussed in the context of multi-seat workstations, classrooms, kiosks, and virtualized environments where multiple independent sessions share hardware. Benefits include improved security and clearer usage accounting; drawbacks include added complexity and potential performance overhead. The term is not widely standardized, and real-world support varies by platform and distribution.

See also: seat (Unix), multi-seat computing, cgroups, namespaces, process isolation, thread scheduling.