Application Freezing when Exporting Graph as SVG

Prerequisites

[ ] Put an X between the brackets on this line if you have done all of the following:
- Running the latest version of Constellation
- Attached the Support Package via Help > Support Package
- Checked the FAQs: https://github.com/constellation-app/constellation/wiki/FAQ
- Checked that your issue isn’t already filed: https://github.com/constellation-app/constellation/issues
- Checked that there is not already a module that provides the described functionality: https://github.com/constellation-app/constellation/wiki/Catalogue-of-Repositories

Description

When exporting to SVG, users are presented with the option to select the number of processors that they would like to dedicate to the export. Currently users can dedicate all of their processors to the export if they choose meaning that the application has to fight for time on these processors to continue to run the UI and background functions.

Steps to Reproduce

Export a graph with 20000 nodes to an SVG file.
Increase the number of available processors to the maximum value
Interact with the application whilst exporting and watch for UI issues.

Expected behaviour: Limit the number of processors available to the SVGExportPlugin to ensure some a free for the application

Actual behaviour: users can dedicate all processors to the export

Reproduces how often: whenever the users choose to increase the number of available processors

Additional Information

The issue can easily be fixed by amending the maximum number of processors available for the export in the file au.gov.asd.tac.constellation.plugins.importexport.svg.SVGExportPlugin.Java

IntegerParameterType.setMinimum(exportCores, 1);
IntegerParameterType.setMaximum(exportCores, Runtime.getRuntime().availableProcessors());

The trick will be to determine how many processors should be left for the application.

constellation-app / constellation