Overview

A typical way of starting your escript script myscript.py is with the run-escript commandThis command was renamed from escript (used in previous releases) to avoid clashing with an unrelated program installed by default on some systems. Most 3.1 releases of esys.escript allow either run-escript or escript to be used but the latter name will be removed in future releases:

escript myscript.py

as already shown in section 1.2. In some cases it can be useful to work interactively e.g. when debugging a script, with the command

run-escript -i myscript.py

This will execute myscript.py and when it completes (or an error occurs), a python prompt will be provided. To leave the prompt press Control-d.

To start run-escript using four threads (eg. if you use a multi-core processor) you can use

run-escript -t 4 myscript.py

This will require escript to be compiled for OpenMP [27].

To start run-escript using MPI [23] with $8$ processes you use

run-escript -p 8 myscript.py

If the processors which are used are multi-core processors or multi-processor shared memory architectures you can use threading in addition to MPI. For instance to run $8$ MPI processes with using $4$ threads each, you use the command

run-escript -p 8 -t 4 myscript.py

In the case of a super computer or a cluster, you may wish to distribute the workload over a number of nodes. For example, to use $8$ nodes, with $4$ MPI processes per node, write

run-escript -n 8 -p 4 myscript.py

Since threading has some performance advantages over processes, you may specify a number of threads as well.

run-escript -n 8 -p 4 -t 2 myscript.py

This runs the script on $8$ nodes, with $4$ processes per node and $2$ threads per process.