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I am not quite sure if this is a reasonable request. May be there are other solutions to my problem. I am not that familiar with MAT. While searching for a memory leak I created several heap dumps and analyzed them (Dominator Tree). I found a lot of retained objects that simply stay with a fixed size. But others are varying in their size. And one object's size was constantly growing! I would love to have the possibility to analyze the dominator trees of several heap dumps.
I started some work to allow tree comparisons in bug 361631 but this may not be useful yet. It seems to compare using the full IObject.getDisplayName which includes the address so won't be helpful across dumps. Grouping the dominator tree by class doesn't work as I thought, as the class name includes the address.
It seems that Netbeans 7.1 supports something similar: http://java.dzone.com/articles/comparing-heap-dumps-netbeans
The compare basket is the standard way to compare dumps, and by comparing histogram tables you get to see how the numbers of objects differs between dumps: http://help.eclipse.org/indigo/index.jsp?topic=%2Forg.eclipse.mat.ui.help%2Ftasks%2Fcomparingdata.html For version 1.2 I'm looking at comparing trees as well as tables. Currently the comparison works on the original format of the tree, so even if you regroup the dominator tree by class the comparison still takes the original format of an object tree. By launching the dominator tree from the search queries command line and issuing this command: dominator_tree -groupby BY_CLASS then the dominator tree is grouped by class which might make a better base for the comparisons.
How well does comparing dominator tree by class work for you?
I know this is a very old request, but I have just made some improvements. The snapshot builds https://www.eclipse.org/mat/snapshotBuilds.php now have some queries to compare dominator trees. See Leak Identification > Compare Snapshots Leak Report This uses deltas in retained sizes when dominator trees from two snapshots are compared.
Created attachment 286513 [details] Dominator tree comparison report Example of how the Leak Suspects by Snapshot Comparison report generates a comparison of the two dominator trees :
I hope this is sufficient, if not then please open a new enhancement request.
