There appears to be an issue in hugo that causes pages in a larger blog to be randomly generated (or not...). About 50% of the pages are there the rest is not but the reported totals at the end of the run are always the same.

Setting the number of processors in main.go to '1' seems to be a work-around for this problem (which suggests a race condition of sorts but I'm a total 'go newbie' so I don't feel qualified to start ferreting it out), after that the generated content is the same for every time the program is run.

If you want to aid reproduction I can supply an archive of the site that has this issue (jacques@mattheij.com).