[Vm-dev] Why the context become a root

Mathieu Suen mathk.sue at gmail.com
Tue Nov 20 14:27:37 UTC 2007

On Nov 20, 2007, at 12:32 AM, Andreas Raab wrote:

> Mathieu Suen wrote:
>> Ok so IIRC adding object into the root table that do not contain  
>> young object do not bug the system.
> Yes.
>> but every object that contain young object should be inside this  
>> table otherwise the gc crash?
> Yes.
>> Next question is where do the root table is update to remove the  
>> object that dose not contain young one?
> It's expensive. For every store into the old object you'd have to  
> check whether it is still a root (which is a linear scan over the  
> object itself so if it is large it'll be very slow).
>> I suppose when a full gc is trigger but is there any other moment?
> Yes. When tenuring, the roots table is cleared. A couple of days ago  
> I toyed with a variant of the collector which used generation aging  
> (e.g., tenures objects after it survived so many GCs) and the main  
> task was deciding whether tenuring should make all tenured objects  
> root or if it should actually scan them (I think it needs to).
> What are you working on?

Nothing special I am just curious and want to learn more about VM stuff.

> Cheers,
>  - Andreas


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