Confusion on Garbage Collection and Heap Dump data

Question

I tried triggering a couple of heap dumps in our application server at a particular time. Also on that time, I noted the garbage collection data.

I was trying to match the Tenured Data parameters with the value of the free & available heap from the heap dump and it doesn't match. Got me confused. Should they be equal or not?

Should Total consumed heap at a particular time be equal to Tenured Data (before) at the same time? if no is the answer, how can I match garbage collection data with heap dump data to make sure the data I am getting is correct?

Answer 1

Collect Garbage collection data using -verbose:gc this consist the exact GC occupancy details similary collect Heapdump on user event. Load the Heapdump in https://www.ibm.com/developerworks/java/jdk/tools/memoryanalyzer/ to get the heap dump details and the verbose gc logs on https://www.ibm.com/developerworks/java/jdk/tools/gcmv Match the details you will get the information you required.