Advanced tips and tricks

This page covers some of the really low-level detail that should not concern most users, but advanced users may find helpful.

Java options

Java provides a generic framework for changing the run-time characteristics of Java applications such as RiskScape. For example, you can set the locale that the program uses (for Internationalization) or change how things like garbage collection behave.

There is a wide range of potential settings that can be configured for Windows or Linux.


Some Java options may vary depending on the version of Java you are using. Currently RiskScape is supported on any Java version between 8 and 17.

You can change Java system properties by setting one of the following environment variables:

  • JAVA_TOOL_OPTIONS - note that these settings apply to all Java programs, not just RiskScape.

  • RISKSCAPE_OPTS - these settings only apply to RiskScape.

In addition, Java also supports _JAVA_OPTIONS and JVM_OPTS (Linux) and JAVA_OPTS (Windows). However, there is less universal support for these latter environment variables, as they tend to be either platform-specific or undocumented.

As there are multiple different ways of setting Java system properties, the following precedence takes effect:



  3. Any system properties that RiskScape might set by default.


For example, to set Java environment variable(s) for RiskScape on Windows, use:


To set Java environment variable(s) for RiskScape on Linux or Mac, use:


These example commands will only take effect in your current terminal. As soon as you open a new terminal, Java will revert back to its default settings.


We recommend you check with the RiskScape community first before experimenting, as changing Java system properties could have a detrimental effect on RiskScape behaviour.

Java memory utilization

Java’s default memory settings are usually good enough for running simple deterministic RiskScape models. However, you may want to alter the Java memory settings if you:

  • Have large models to run, e.g probabilistic models

  • Have large amounts of free memory on a server that you want to utilize

  • Get an Exception in thread "main" java.lang.OutOfMemoryError: Java heap space error running your model

How much memory RiskScape uses is largely controlled by the Java heap size. When more memory is available (i.e. the heap size is larger), the model tends to run faster because Java spends less time doing things like garbage collection.

The default heap size will vary depending on your computer, but it will typically be 25% of the available memory. The maximum heap size can be changed with one of the following java options:

  • -Xmx<size> to set maximum heap size to an absolute value, e.g -Xmx24g to use 24GB of RAM for the Java heap

  • -XX:MaxRAMPercentage=<size> to set maximum heap to a percentage of the system’s total RAM, e.g -XX:MaxRAMPercentage=50 to use half the total RAM for the heap


The Java heap size is a generic Java Virtual Machine (JVM) setting, so you can find more help about how to configure it online.

When choosing a maximum heap size you should:

  1. Work out how much total RAM is present on your machine.

  2. Subtract the memory needed for running other applications, i.e. check the current ‘free memory’ and then subtract some extra slush.

  3. Allow some additional overhead for running RiskScape itself. Java applications consume additional memory besides just the heap, i.e. libraries, threads, etc. This additional memory will vary depending on what RiskScape plugins you use (e.g. HDF5, CPython, OGR).


Setting the maximum heap size too high may over-subscribe memory and can result in RiskScape exiting with an out of memory error. On Linux, this may simply appear as RiskScape being ‘Killed’.

There are many other options that could be used to tune memory management. Refer to the Java 17 tuning guide for more details.

Windows quirks

Using quotes in the terminal

Generally, it’s recommended to always use double-quotes when specifying parameters for the riskscape model run command.

However, Windows users may experience annoying terminal behaviour where the quote mark won’t be displayed immediately after it is typed. To check if this problem affects you:

  1. Open the Windows terminal.

  2. Type the quote character, i.e. ' or Shift and '.

  3. If nothing is displayed, press the space bar. The quote mark should now be visible.

This appears to be a known issue on Windows.

Anecdotally, we have seen this problem resolve when unnecessary additional language packs were uninstalled. To check what language packs you currently have installed, select Settings -> Time and Language -> Language and then look under ‘Preferred languages’.

Shell scripting

For an example of using RiskScape to loop over hazard files, see Running the same model repeatedly. If the riskscape model batch command is not quite right for you, then you may be able to use shell scripting to run RiskScape commands repeatedly.

Your terminal will usually support some sort of for loop, that will let you iterate over a set of values. The syntax for this will vary depending on what operating system and terminal you are using.

For example, in the Windows Command Prompt, the following statement will loop through a set of GeoTIFFs in the data directory, and use them as the input hazard-layer for your model.

for %f in (data\*.tif) do riskscape model run MODEL_NAME -p "input-hazards.layer=%f" --output=output\%~nf

Wheres on Linux, the following bash code will do the same thing.

for f in $(ls data/*.tif) ; do riskscape model run MODEL_NAME -p "input-hazards.layer=$f" --output=output/$(basename $f) ; done

Batch scripts

Getting the for loop command right can be a little tricky. An alternative approach is to save the commands to a script file and then run the file as needed. On Windows, this is called a batch file.

Below is an example of a Windows batch file that runs every model in the Getting started modelling in RiskScape tutorial project. The :: lines are comments that explain what the script does.

:: Make sure riskscape is present on our PATH
:: (update this to match your RiskScape installation directory)
set PATH=%PATH%;C:\RiskScape\riskscape\bin

:: change to the directory that contains our project file
cd C:\RiskScape_Projects\getting-started

:: define in a variable the models in our project that we want to run
set models_to_run=basic-exposure exposure-reporting exposure-by-region

:: loop through the models specified and run each one
for %%x in (%models_to_run%) do (
    call echo Running: riskscape model run %%x
    call riskscape model run %%x

:: don't close the terminal when we're done
echo DONE!

If things are getting repetitive, you can nest multiple for loops together. For example, the following batch file snippet would run all GeoTIFFs in a directory through a series of different models.

for %%f in (data\*.tif) do (
    for %%x in (%models_to_run%) do (
        call echo Running: riskscape model run %%x hazard=%%f
        call riskscape model run %%x -p "input-hazards.layer=%%f" --output=output\%%x\%%~nf


To avoid nested for loops, you could alternatively combine the riskscape model batch command with a single for loop. This would let you iterate through multiple different things, without the batch file getting too complicated.