Out Of Memory errors

OutOfMemory errors are usually reported by this kind of error dialog:


Note that this bug report dialog may not always be shown as displaying it needs a little memory.

The memory used by Java programs is bounded by an upper value which depends on which version of JANIS you use : downloaded or via Java Web Start. "Out of Memory" errors occurs when this limit is hit.

You can check the limit which appy to you in the JANIS About Box or in the bottom right corner of JANIS main window:

AboutBox and Browser memory 

In the About Box:

  • "500MB max" means that 500 MB of memory will be used by JANIS at most, "Out of Memory" errors will occurs if more is needed.
  • "184MB total" is the memory currently allocated on your computer by JANIS
  • "165.88MB free" means that 184 - 165.88 ≈ 19MB are currently used by JANIS

The bottom corner of JANIS's main window displays the 19MB of memory currently used and the upper limit of 500M, contrary to values displayed in About Box, the values here are dynamic.

NB: it is normal to see the amount of memory used by JANIS slowly increasing and regularly dropping down, even if you do not do interact with the application.

Downloaded version of JANIS


You can change the upper limit of memory usable by JANIS by editing the janis.bat file:

start javaw -Xms100M -Xmx512M -jar Janis.jar

You may either remove the -Xmx512M option and let the Java use the default value which apply to your system. With a recent 64bit Java (8 or newer) the default is usually 1/4 of your computer memory.

Or you could change the value in the -Xmx option, e.g. to set it to 1 GB:

start javaw -Xms100M -Xmx1024M -jar Janis.jar


Apply the instructions for Windows to the janis.sh file:

java -Xms100M -Xmx512M -jar Janis.jar

Either remove or edit the -Xmx option.

Mac OS X application bundle

An upper limit of 512 MB is set in the application bundle.

Please contact janisinfo@oecd-nea.org is you need help to change it.

Java Web Start version

The upper limit of memory usable by JANIS depends on your system and your Java version. With a 64bit Java (8 or newer) the default is usually 1/4 of your computer memory.


Contact: janisinfo@oecd-nea.org

Related topics
  • JANIS Help