[M3devel] GC question

[Darko]

Yep, I want to replace one object with another. One application is to  
expand open arrays without searching large data structures for  
references to replace. Maybe a simpler question is can you increase  
the size of an allocated object without getting messy?


On 14/01/2008, at 1:17 PM, Tony Hosking wrote:

> I'm not sure what your purpose here might be.  You shouldn't assume  
> anything about an object's precise location since the collector is  
> free to move it around.  What are you trying to do?  If you are  
> trying to *replace* one object with another and have all references  
> to the old object refer to the new object, then, yes, you really  
> need to get intimately involved with the GC, since it will need to  
> go through the whole heap and redirect those references.  It is  
> doable, but messy, and probably requires that all threads in the  
> system be stopped while you pull off the switch.  To do it without  
> stopping all the threads requires that you do something much smarter  
> (see papers on replicating GC...).
>
> On Jan 14, 2008, at 3:53 PM, Mika Nystrom wrote:
>
>> It would have to be able to return an error, no?  If there's
>> an ambiguous root pointing to the object...
>>
>>
>> Darko writes:
>>> Tony,
>>>
>>> I imagine you're intimately familiar with the garbage collector
>>> implementation. If I wanted to implement a 'reallocate' function  
>>> that
>>> preserved references to an object although the object was  
>>> reallocated,
>>> ie change all existing references from the old object to the new
>>> object, would this be straight forward using the code of the current
>>> GC implementation? Is there any existing function that might do
>>> something like this already?
>>>
>>> Thanks,
>>> Darko.
>