Scripting languages let users rapidly compose assemble existing programs into more powerful applications. In parallel scripting, users apply parallel composition constructs to existing sequential or parallel programs to develop highly parallel applications.

Parallel scripts are quite flexible and portable, and can run efficiently on platforms ranging from multicore workstations to petascale supercomputers. For many applications, like parameter sweeps and data analysis, parallel scripting is easier, more accessible, and more productive than tightly-coupled parallel programming.

In this talk, we will describe how the Swift parallel scripting system (www.ci.uchicago.edu/swift) is used to run scientific applications on petascale systems like IBM Blue Gene/P and Sun Constellation. We