Re: What does it mean when gwt-unitCache-... is out of sync exactly??

[Jens]

It caches compilation artifacts (GWT compile and DevMode) so that iterative development is faster. 

When Eclipse says that this resource is out of sync with your file system it pretty much means that Eclipse has detected changes to these files since the last time Eclipse has read-in these files. You can right click the folder and select "refresh" from the menu so that Eclipse will re-read the files. You normally have to do this when you want to delete the unit cache folder within Eclipse to force a full recompile. 

The cache does not affect browser memory usage at all, its just there to speed up compilation/DevMode by reusing cached artifacts. To measure browser memory usage you have to use tools provided for your OS and/or browser. In Google Chrome for example, you can type in "about:memory" to see some basic memory stats per browser tab.

-- J.