I just tagged release 1.6 of dupd.
See the ChangeLog for a list of changes.
As usual, there is not much in the way of directly user-visible changes. It should continue to work as it did. If not, let me know.
One change worth pointing out is that the HDD mode is now the default (a new option, –ssd, allows selecting the SSD mode). I’m on SSDs myself and generally use the SSD mode so why the change? Well, the HDD mode is a more conservative default because even though the SSD mode is often faster it is also true that the SSD mode can be dramatically slower in worst-case scenarios.
One downside of the HDD mode is that it uses more RAM. I haven’t seen it use excessive memory with any real-world file sets I have but in theory it could. If you run into this, there is a new option to limit buffer sizes (see man page).
Although not user-visible, this release does contain a significant rewrite of several subsystems (dir and path storage, thread work queues). So let me know if any bugs surface.