> If each thread is doing it's own random generation then it's difficult to compare results between using 1 thread and 2 threads, because it's no longer the sam

> If each thread is doing it's own random generation then it's difficult to compare results between using 1 thread and 2 threads, because it's no longer the same single stream of random data Most modern RNGs support a "jump" operation that takes care of this; PCG has the best standard API I've ever seen. Alternatively, with any RNG you can interleave (call `next` numthreads times before selecting a number) but that's slower.