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From "Alois Reitbauer" <alois.reitba...@dynatrace.com>
Subject RE: Round tripping entity identity
Date Mon, 21 Sep 2009 20:52:11 GMT
Steve, others,

we at dynaTrace are using the current JVMTI/JVMPI APIs where weg et the
"tags" for each object. Those tags are necessary because of current API
restrictions. However this approach is not practical for big dumps as
you at least require a long to identify one object. For large heaps (>
1.5 GB) this will result in massive memory overhead.

I am by the way more than convinced that we will also need a spec for
another native API that just for one that supports reading dumps. Tools
like others cannot rely on the dump creation capabilities of JVMs for a
number of reasons. If you want I can elaborate more on that.

- Alois

-----Original Message-----
From: Steve Poole [mailto:spoole167@googlemail.com] 
Sent: Dienstag, 08. September 2009 06:11
To: kato-spec@incubator.apache.org
Subject: Round tripping entity identity

It's important for performance and scalability reasons that the API does
not
force the loading of a complete dump into memory.

What that means in practise is that the application using the API will
need
to be able to read entities in a "random access" manner.  That in turn
means
that we need a mechanism that can provide a "handle" to an entity and a
way
for the API to convert the handle back into an full representation of
the
entity in question.

Since the handle will probably have to be stored outside of Java (ie in
a
database)   the handle has to  be a primitive data type.

Is this a reasonable view?

The MAT tool is the only example I have to date where this mechanism is
needed  -  I believe they use a long rather than a String.

Are there other uses we should consider?  -  What about cross dump
corrolations?

Cheers

Steve

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