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Editorial Team
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Asked: 2026-05-13T06:52:34+00:00

Currently I am working on a Java agent to assemble memory stats. With the

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Currently I am working on a Java agent to assemble memory stats. With the help of the instrumentation API I can get a hold of the classes (and manipulate them). With plain Java I can get an estimate of the resources used for each object. So far, so good.

The question I am faced with right now is "how to get a hold of every Object instance of a specific class". I can do byte code manipulation in order to get a hold of the object instance, but I was hoping there is another API I am not aware of, helping me to accomplish my goal without such a rather heavy intrusive step. At the end, the performance impact should be kept to a minimum. Any ideas?

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  1. Editorial Team

    The debugger in Eclipse can show you all the instances of a class, so I looked around Eclipse’s sources. Eclipse uses the Java Debug Wire Protocol, which allows you (since Java 6) to look up all the instances of the requested class. If you want to go down this path, grab a copy of Eclipse sources and check out the instances method of org.eclipse.jdi.internal.ReferenceTypeImpl.

    A simpler way is to use the Java Debug Interface. Note the ReferenceType.instances method.

    I still haven’t figured out how to use JDI to connect to a running process and how to obtain an instance of ReferenceType. The JDK contains several examples, so I’m sure it’s doable.

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