SBCL Fibers – Lightweight Cooperative Threads

SBCL Fibers is a work-in-progress implementation of lightweight cooperative userland threads for Steel Bank Common Lisp, featuring carrier-thread-based scheduling, zero-allocation context switching, and deep garbage collector integration with conservative stack scanning. The system includes a Chase-Lev lock-free work-stealing deque, TLS overlay arrays for dynamic variable bindings, fiber-aware blocking primitives, and cross-platform I/O multiplexing via epoll, kqueue, and poll.