RFR(M, v7): JDK-8059036 : Implement Diagnostic Commands for heap and finalizerinfo (original) (raw)

Mandy Chung mandy.chung at oracle.com
Wed May 20 23:07:21 UTC 2015

On May 19, 2015, at 11:51 PM, Dmitry Samersoff <dmitry.samersoff at oracle.com> wrote:

Other alternatives could be to do all hashing/sorting/printing on native layer i.e. implement printFinalizationQueue inside VM. Both options has pros and cons - Java based solution requires less JNI calls and better readable but takes more memory. It might be better to return an array of Map.Entry<String, int[]> objects to VM rather than one huge string.

The output and formatting should be done by jcmd. What you really need to get a peek on the finalizer queue and print the histogram. The VM has the heap histogram implementation. Have you considered leveraging that?

5: 1012 40480 java.lang.ref.Finalizer

You can find the registered Finalizer instances. The downside is that icmd -finalizerinfo stops the world. I think it’s not unreasonable for this diagnostic command to be expensive like -heap command.

Mandy

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