ExterniaJ Sorting on a Distributed Memory Machine

Sorting is a classic problern[5], which naturally lends itself to parallel processing. Many researchers have investigated memory-based parallel sorting [3], but only a few researchers have inve,stigated the piroblem d parallel external sorting[2, 41. Existing algorithms employ local sorting of runs followedby pipelined merging of runs. The writing of the final merged result is a serial process performed by a single processor. This sequential bottleneck has a significant negative impact on the total sort time. It also does not make effective use of the concurrent I/O capabilities provided on ai number of parallel machines. I have proposed and prototyped a two phase parallel external sorting algorithm that removes the “final merge bottleneck” by partitioning sorted imns anid utilizing multiple processors to build a merged Iun.