[concurrency-interest] @Contended (JEP-142)
Alan.Bateman at oracle.com
Fri Nov 30 09:08:43 EST 2012
On 30/11/2012 13:36, Vitaly Davidovich wrote:
> What's the plan for making this info available in heap dumps (taken
> using jmap)? I'd imagine tools like Eclipse MAT may want to indicate
> that a given instance of a class has padding applied. Otherwise, the
> object size reported won't match expectation (without knowing that
> padding was applied).
jmap triggers HotSpot to generate a heap dump in HPROF format, a format
that is VM agnostic. The header allows for the word size but that's
about it. This means that tools don't have the details on the actual
layout, don't know about padding etc. from looking at the heap dump. It
is an area that does need to be re-visited (for many reasons).
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