Whoops! fixed a bad bug whereby each map was being output to the same file. Not sure if the fix is very elegant but at least it's not being silly any more. Now limits the default value of max-jobs to 4 no matter how many cores you have as further testing shows that having more threads just burns CPU cycles but doesn't actually finish any quicker. I guess the memory system is limiting the performance and the CPUs are spinning waiting for access. Now showing a real speedup of around 240% (my earlier higher claim was based on CPU usage and I now realise that was erroneous, sorry). -------- Now defaults to creating a thread per core so without doing anything you should see a speedup on a SMP box when processing multiple maps. You can use --max-jobs=N to limit the concurrency - you may want to specify that if you can't increase the VM size to what is required. However, it occurs to me that if you can afford a box with more than 2 cores, then you can probably afford a reasonable amount of memory (otherwise, what's the point in having more cores?) Added help blurb. -------- OK, let it not be said that I don't listen to others! The attached patch provides support for making maps in parallel. By default, the behaviour is the same as before but if you specify --num-threads=N where N is greater than 1, it will process N maps at the same time and then combine the results (if required). Don't forget to increase the heap size appropriately. A quick test on the big box shows good speedup - specifying --num-threads=4 and 2GB VM size. I was seeing better than 380% utilisation with 8 cores in use. I suspect the performance limitation here will be VM size and memory system bandwidth. BTW - I don't think num-threads is actually the best name for the option, so please suggest alternatives. Cheers, Mark