1. A method, comprising: determining computational resource capacity characteristics from historical usage data relating to use of a heterogeneous inventory of computational resources, the computational resource capacity characteristics comprising a trace history representative of the availability of various components of the heterogeneous inventory of computational resources at various points in time; calculating a plurality of finishing times for a project by performing a plurality of simulation runs based on respective sets of respective amounts of available computational resource capacity represented by different respective portions of the trace history, wherein each of the plurality of simulation runs begins at a different time in the trace history; assembling the plurality of finishing times into a distribution; constructing a risk measure using the distribution; and facilitating selection of a portfolio for the project from the heterogeneous inventory of computational resources based on the risk measure and the plurality of finishing times; wherein the determining, the calculating, the assembling, the constructing, and the facilitating are performed by a computer.