Hi @jamesc ,
You can try to use a WoW tool named VisualVM (https://visualvm.github.io/ ) to analysis the memory of java.
Here is my analysis process of GC overhead limit exceeded
error.
https://forum.orekit.org/t/java-lang-outofmemoryerror-gc-overhead-limit-exceeded/1461/4?u=lirw1984
Best,
lirw