Possible Memory Leak?

Question

I've got a running java webapp, that I'm monitoring with visualVM.

Here's the graph of the heap:

The was tested with two sets of requests, one at 3:20 and the other at 4:40 aprox (they are represented in the graph as the only two peaks).

My question is: does this means I have a memory leak? I'm worried about the middle part where, although the GC runs, the heap stays in 250MB all the time.

Thanks a lot for your insights.

Answer 1

The first request at 3:20 caused some memory to be held, but notice that the GCs after the second request reclaimed most of it. Also I think that major GC was performed only after the second request at 4:40.

It looks like there is no leak. My theory is that the request at 3:20 caused the young generation to fill up, and the resulting minor GC promoted some objects to older generation. The next major GC, caused by the request at 4:40 cleaned most of those up.

You can verify this by using a profiler to mark the heap before issuing the same request as the one at 3:20, forcing a full GC, and then checking what objects are lingering. I am not sure if VisualVM lets you (1) mark the heap and (2) force a full GC, but OptimizeIt used to do it.