[platform-core-dev] How much memory can a Workspace take?

Hi fellow committers,

I got a report about an OutOfMemoryError generated during a Workspace Refresh operation. When looking at the .hprof file with the MemoryAnalyzer, it turned out that pretty much all the memory was taken by core/Workspace only:

100 MB (53%) in org.eclipse.core.internal.resources.Workspace (occupied by ElementTree)
52 MB (27%) in org.eclipse.core.internal.dtree.DeltaDataTree (this is a different additional DeltaDataTree)
37 MB all the rest

The workspace was arguably very large, but still I am surprised

that the numbers are that large
that in addition to the Workspace, there is such a large additional DeltaDataTree,
that I see an OutOfMemoryError reported with 189MB total where I used -vmargs -Xmx320m ... what happened to the extra 131MB ?

Do my numbers sound reasonable, or could there be a bug that leads the Workspace to take an excessive amount of memory? How much memory do we expect a workspace to take for, say 50000 files? How much *additional* memory may a workspace delta take that is generated during a Refresh? Would any additional investigation using the Coretools make sense at this point?

I can make the .hprof file available on request (it's a 200MB ZIP file).

Many thanks for any pointers!