Message-passing and shared-data programming models - wish vs. reality

Typically, only technical arguments like performance, cost or scalability are discussed if programming models and languages on high performance computing facilities are under consideration. In this paper, we investigate the impact of human factors such as personal preferences and perceptions, and personal experience on making technical decisions. We have queried a large HPC community of the Sharcnet project in Ontario in regards to general preferences and in regards to detailed usage of language features and programming style. The main result of our study is that - as often claimed in the past but never proven - shared-memory programming models and architectures appear to be the ideal for the majority of users, even if the main architecture of the project is a distributed-memory cluster. However, experience appears to be able to quickly overcome initial difficulties in using message passing.