Why an empty Java app consumes memory? [duplicate]

Question

I'm exploring memory usage in Java to understand why my program leaks memory. After stripping off code in my main while loop, I still get an increase of memory usage over time. Pondering the memory usage of an empty program:

class Nothing
{    public static void main(String[] args)
     {    while(true);    }
}

I still saw an increase of memory:

So my question is: Why is there still a saw tooth pattern? Why when the GC runs does it not save all the memory (each time the gc runs (the valleys) the used memory increases by 10-20Kb (compared to the previous valley))?

EDIT:

java version "1.6.0_29"

Java(TM) SE Runtime Environment (build 1.6.0_29-b11)

Java HotSpot(TM) Client VM (build 20.4-b02, mixed mode, sharing)

OS: Windows 7 Enterprise-32 bit

Answer 1

This is an artifact by the profiler, without the profiler there will be no allocations. Different profilers produce different artifacts, depending on how they record data. Below you see what profiling Nothing JProfiler will look like:

Much less of a sawtooth pattern. However, there is also a minuscule memory consumption:

which is due to the fact the profiling agent polls the java.lang.management.MemoryUsage JMX bean. Eventually this consumption will also trigger a garbage collection.