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10.14. Java Heap Errors


'Heap" is the memory of the computer that is available for an application to use.  Applications create objects which they place into the heap.  When the application is finished with the objects, they remove those objects from the heap.  If you are receiving messages that reference Java Heap Space, your Assemblage configuration may require more memory than Assemblage uses by default - or your computer doesn't have enough memory for Assemblage to run at it's default heap size.  The default heap size that Assemblage requests is 768 MB.  If your computer can only provide Assemblage with 500 MB when it launches, then Assemblage will reduce it's heap usage to 500 MB.  Note that it is quite possible for a PC with 2 GB of memory to not be able to provide Assemblage with the full 768 MB RAM due to memory segmentation.

Before you read further: Sometimes this problem is not caused by memory. Open up the Excel file used to map your assemblies and make sure there are not a lot of extra empty lines at the bottom of your data. If you find that you do, then delete the extra lines, re save the excel and try again.

If your Assemblage configuration has a moderate number of assemblies (100-300), then heap space errors are probably caused by a lack of memory on your PC.  We recommend a minimum of 4GB of RAM.  And more if your operating system supports it.

If your Assemblage configuration results in a very large number of assemblies, you may need to increase the amount of heap space that Assemblage will use.  In order for this to work, your PC must have a large amount of available RAM, and be running Assemblage version 1.1.62 or higher.


To adjust the Assemblage heap size, you will need to be on Assemblage 1.1.62 or higher, and adjust the shortcut you use to launch Assemblage to control the size of the heap that will be requested.

Right click on your shortcut, and choose Properties.


Update the Target field to include

 /maxheap=### (where ### is the size of the desired heap in MB). 

In the illustration above, the heap size that Assemblage will request is 1.5 GB or 1500 MB.

Note:  This will only work if the workstation has a lot of memory (RAM)

Note:  If your PC does not have enough continuous RAM to allow the heap size you specify, Assemblage will automatically reduce the RAM it uses (even if that is less than you requested in the /maxheap setting).

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