psort, yet another fast stable external sorting software

psort is a fast, stable external sorting software available as a binary executable that can sort a disk file interpreted as a sequence of r byte records according to a key of k bytes starting from the i byte of each record. psort is also available under GPL as a C library, allowing one to define one’s own key comparison functions, as well as key preprocessing and postprocessing functions to increase the efficiency of comparisons. psort can sort 108 · 2 = 1, 811, 939, 328 records of 100 bytes each, according to an initial 10 byte random key, on a 392.78 U.S. dollar desktop machine in less than 2408.6766 ≤ 3·365·24·3600 39278 seconds i.e. for less than 1 penny according to the Pennysort Daytona Benchmark. A version of psort hand optimized for the Pennysort (Indy) Benchmark can sort a slightly larger input file of 113 · 2 = 1, 895, 825, 408 byte records on the same machine in the same time.