Note from THE FUTURE about PDL parallel processing:

• In 1998, PDL version v1.99987, there was extremely basic support for POSIX threading
• In 2011, John Cerney added PDL::ParallelCPU and the machinery for doing "broadcasting" (then, confusingly, called "threading") to "pthread" over a specified number of CPUs/cores, first released with 2.4.10
• In 2021, 2.058 added the ability for this to take place over ndarrays with dimensions not exactly divisible by the given number of cores
• 2.059 then added a default value for the number of cores as the available number of cores at program startup (found using code lifted from git)