I have recently parallelized 3D flood fill algorithm, it’s essentially a graph search on a 3D grid of nodes. More precisely, the problem is known as connected-component labeling: https://en.wikipedia.org/wiki/Connected-component_labeling

The solution is to keep partitioning until you saturate all cores. As soon as all saturated, stop partitioning and compute. As soon as any task finished, resume partitioning.

On the lower level, I used a thread pool. BTW, the infrastructure for that is built-in in Windows, see SubmitThreadpoolWork API: https://docs.microsoft.com/en-us/windows/desktop/api/threadp...