uThreads – Concurrent User Threads in C and C++

In plain words

uThreads is a C++ library that provides lightweight concurrent user-level threads, also called fibers, using cooperative scheduling. These threads run on top of kernel threads to deliver concurrency and parallelism while avoiding the overhead of kernel-level preemption and scheduling. uThreads is designed for developers who need efficient multithreading without the performance costs associated with traditional operating system threads.

written from the facts on this page · September 2026

From the sources

uThreads is a concurrent library based on cooperative scheduling of user-level threads(fibers) implemented in C++. User-level threads are lightweight threads that execute on top of kernel threads to provide concurrency as well as parallelism. Kernel threads are necessary to utilize processors, but they come with the following drawbacks: Cooperative user-level threads, on the other hand, provide light weight context switches and omit the additional overhead of preemption and kernel scheduling. Most Operating Systems only support a 1:1 thread mapping (1 user-level thread to 1 kernel-level thread), where multiple kernel threads execute at the same time to utilize multiple cores and provide…from samanbarghi.com

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