How runtime memory is calculated

I am new to Code-chef, after submitting the solution summary shows the memory which is used by my program. Can anyone please explain me, How they are calculating the memory used.

As Code-chef supports so many languages, I wonder if they use same method for every language or different methods.

This feature in SPOJ back-end system is not very good.

My opinion is, that they run the program and check what amount of memory was consumed. But for java program this is memory for whole java JVM - always the same number.

“that they run the program and check what amount of memory was consumed” It didn’t occur to me that they are running the program & calculating the memory…
I asked for explanation how they are calculating the memory. Can u please explain that