A new package is now on the ghrr drat. It was uploaded four days ago to CRAN but still lingers in the
inspect/ state, along with a growing number of other packages. But as some new packages have come through, I am sure it will get processed eventually but in the meantime I figured I may as well make it available this way.
The idea of prrd is simple, and described in some more detail on its webpage and its GitHub repo. Reverse dependency checks are an important part of package development (provided you care about not breaking other packages as CRAN asks you too), and is easily done in a (serial) loop. But these checks are also generally embarassingly parallel as there is no or little interdependency between them (besides maybe shared build depedencies).
So this package uses the liteq package by Gabor Csardi to set up all tests to run as tasks in a queue. This permits multiple independent queue runners to work at a task at a time. Results are written back and summarized.
This already works pretty well as evidenced by the following screenshot (running six parallel workers, arranged in split byobu session).