Hi Greg,
Is the default for your patch to not become parallel? It seems that making mkgmap parallel is hard, and my personal utility function places correct behavior very high and speed not that much. Until the code is really shaken out, I don't want to run parallel. I don't know what others think, but just a thought.
At this time, it defaults to creating as many threads as there are cores. I don't have a big issue with making the default number of threads = 1 if that's what people want. How about this: 1 - with no option specified, the default number of jobs (aka threads) is 1. 2 - specifying --max-jobs without a value will maximise the number of jobs (i.e. create one thread per core). 3 - specifying --max-jobs=N will create N threads. Would that suit you? Cheers, Mark