Java application memory size

Question

While either IntelliJ or Eclipse are running, I can see how much heap they are using from inside the application from the progress bar at the bottom.. it always indicates a

Answer 1

It is worth remembering that Java allocates the maximum heap size on startup and this shows in the virtual memory size. (This is by default proportional to the amount of memory you have) This can be much larger than the actual main memory used.

I suspect you are looking at this virtual memory rather than the resident memory.

If you use pmap on linux you can see all the memory mapped regions and their sizes.

If a restart IntelliJ with an open project on Windows, it says its using 35 MB of about 100 MB used with a 494 M maximum. In task manager it says the size is 173 MB private and 196 MB total.