C discrete event SIM w stackful coroutines runs 45x faster than SimPy
Hi all, I have built Cimba, a multithreaded discrete event simulation library in C. Cimba uses POSIX pthread multithreading for parallel execution of multiple simulation trials, while coroutines provide concurrency inside each simulated trial universe. The simulated processes are based on asymmetric stackful coroutines with the context switching hand-coded in assembly. The stackful coroutines make it natural to express agentic behavior by conceptually placing oneself "inside" that process and describing what it does. A process can run in an infinite loop or just act as a one-shot customer…
C discrete event SIM w stackful coroutines runs 45x faster than SimPy launched on February 3, 2026 with 69 votes, #529 of 16,627 launches that month and more than 95% of that year's launches.
In plain words
Cimba is a discrete event simulation library written in C that combines POSIX multithreading for parallel trial execution with stackful coroutines for concurrency within each simulation. Processes use asymmetric coroutines with assembly-level context switching, allowing developers to describe agent behavior intuitively from within the process perspective. Processes can run continuously or execute once, yielding and resuming from any call stack depth to act as both active agents and passive objects.
written from the facts on this page · September 2026
From the sources
A multithreaded discrete event simulation library in C, using POSIX pthreads for parallelized trials and replications, stackful asymmetric coroutines for concurrent simulated processes inside each thread, and optionally CUDA or other GP GPU parallelism for detailed model physics inside each coroutine. - ambonvik/cimba
In the maker’s words, at launch
Hi all, I have built Cimba, a multithreaded discrete event simulation library in C. Cimba uses POSIX pthread multithreading for parallel execution of multiple simulation trials, while coroutines provide concurrency inside each simulated trial universe. The simulated processes are based on asymmetric stackful…
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