Question about the mapping of oopDesc and KlassOop

Keith McGuigan Keith.McGuigan at Sun.COM
Wed Feb 18 08:25:41 PST 2009

Colin(Du Li) wrote:
> Hello,
> I have a question about the java object layout in Hotspot.
> In hotspot, a oopDesc respesents a java object, oopDesc contains a pointer
> to a klassOop instance. Is the relation  between the instance of oopDesc and
> the instance of klassOop one to one mapping ? Or multiple oopDesc  instances
> can share one klassOop?
> Thanks a lot!

The latter.  An oopDesc* is a pointer to an object in the java heap. 
Every oop in the heap has a pointer to it's type (the klassOop) as it's 
second field.

- Keith

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