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Is direct children object/vvariable wrong in dominator tree? [message #742203]

Thu, 20 October 2011 05:22

jinjian.1@gmail.com is currently offline

jinjian.1@gmail.com
Messages: 2
Registered: October 2011

Junior Member

In dominator tree, some variables showed as their ancestor's child.

I attached a screenshot, these HTTP response's header should belong to HTTPResponse which is the direct child

Attachment: ObjectTree.png
(Size: 330.00KB, Downloaded 90 times)

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Re: Is direct children object/vvariable wrong in dominator tree? [message #742274 is a reply to message #742203]

Thu, 20 October 2011 06:47

Krum Tsvetkov
Messages: 139
Registered: July 2009

Senior Member

It is fine to have these objects on the same level. In the dominator tree you will see one objet A as a child of another object B only if all paths from the GC roots to the object A go through B. The semantic is the following - if B dominates A, then removing B from the heap should mean that A is also removed.
If you have for example a char[] that is only reference by a single String, then the char[] will be a child of the String in the dominator tree.
However, if there are other Strings also pointing to the same char[], then the char[] won't be a child of any of them in the dom. tree.

Does this makes sense now?

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Re: Is direct children object/vvariable wrong in dominator tree? [message #742972 is a reply to message #742274]

Thu, 20 October 2011 22:22

jinjian.1@gmail.com
Messages: 2
Registered: October 2011

Junior Member

Yeah, Make Sense. In IBM's Heap Analyzer, it have a sign to indicate if the object has been referenced by other object when you click through the object tree. Then you can know if the object is shared by multiple reference, It is more clear about this sharing relationship. but i really like Eclipse Memory Analyzer more because it do more stuff/analysis than just show object relationship and it can run with less memory.

But Do we have a way to indicate real object relationship in Memory Analyzer directly? I tried many ways in analyzer, it seems analyzer can construct class relationship but not object.

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Re: Is direct children object/vvariable wrong in dominator tree? [message #743141 is a reply to message #742972]

Fri, 21 October 2011 02:55

Krum Tsvetkov
Messages: 139
Registered: July 2009

Senior Member

Yes, you can show also object references. You can do this in both directions - refs from an object (outgoing), and refs to an object (incoming).
Open the context menu on any object (or group of objects) and select the top entri - List Objetcs... -> with outgoing references.
You can do this from almost any place (i.e. Dominator tree, class histogram, etc...)

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