Hi There,

we proposed to contribute the Memory Analyzer a couple of weeks ago. Let me give you a better picture of what it is and how it could be of use to Eclipse.

The Memory Analyzer works with HPROF heap dumps. A heap dump is a complete picture of all objects held in memory at a given point of time. One can browse the objects, see why they are not garbage collected (path to GC roots), what memory they keep alive (retained set) and how big that chunk is (retained size).

Okay, that's business as usual, you say. Well, the Memory Analyzer allows you to extend it by something called queries. This is what you can do:

* Group objects by class loader: Any up-to-date architecture loads components with separate class loaders, be it osgi or JEE application servers. The Memory Analyzer allows you to extract meaningful names for different types of class loaders. Thereby one directly sees the object X was loaded by plug-in Y.

* Identify leaking class loaders: Ever seen memory consumption go up after each deploy-undeploy-deploy cycle? This can happen if the component does not de-register itself properly. But how do you find out? Using the Memory Analyzer, one could easily build a query that displays the classes (or class loaders) which should not be there anymore. Of course, to do this, you need the implementation know-how which of the class loaders are valid applications.  For example, we know our application server keeps a reference to valid class loaders in some registry. So all class loaders not contained therein are suspicious. We extract those suspects for further analysis. This type of query is also applicable to Eclipse Plug-ins and/or other open source servers.

Other highlights that come to my mind: The Memory Analyzer works on multi-GB production heap dumps. Actually, that is the reason why we started developing the tool in the first place. We couldn't find other tools that enabled us to look into a 50 million object heap dump.

And one more thing: the retained size of any object is directly available. And the retained sizes of arbitrary object sets can be approximated very quickly. This is important as the retained size is the most important indicator when looking for memory leaks.


More Details:
http://www.eclipse.org/proposals/memory-analyzer/
https://www.sdn.sap.com/irj/sdn/wiki?path=/display/Java/Java+Memory+Analysis


Kind regards,

   - Andreas.