System Design

System Design

This section describes how the software is configured to take advantage of the hardware (see Computing Environment for details on the hardware and software used in the travel model; see Setup and Configuration for details on setting up and configuring the SANDAG model to run on a given set of hardware).

Household Manager and Matrix Manager

Before executing a model run, the travel model requires a Household Manager and a Matrix Manager to be created. In the SANDAG model application, the Matrix Manager resides on the same machine as the main CT-RAMP client process. The Matrix Manager is tasked with managing all of the skim matrices used by the choice models. When a skim is needed, a request is made to the Matrix Manager, which then reads the required skim from disk and stores it in memory. Once in memory, each matrix is available to any other JPPF node process that may need it.

The Household Manager is tasked with managing the simulated households, as well as each simulated person in each simulated household. The Household Manager provides the JPPF nodes with information regarding the households for which the JPPF nodes are applying choice models and stores the resulting information computed by the JPPF nodes. To help keep run time down, the synthetic population is read from disk and stored in memory at the beginning of the application and then continuously updated as choice models are completed and iterations are performed. When the last iteration is complete, the necessary information is written to disk.

Both the Household Manager and Matrix Manager have substantial memory footprints.

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