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From Etienne Gagnon <egag...@sablevm.org>
Subject Re: [drlvm] Class unloading support - tested one approach
Date Thu, 09 Nov 2006 16:39:30 GMT
Etienne Gagnon wrote:
> Salikh Zakirov wrote:
> 
>>I have another concern though: 
>>just before starting "final unloading" collection, we scan vtable marks and identify
>>the candidates for unloading. During the "final unloading" collection, the
>>candidate classloader roots are reported as week. At the end of the trace,
>>we need to rescan vtable marks and "revive" the classloader which were found
>>in possession of live objects. This techniques is exactly the same as the one
>>used for object finalization. 
>>
>>However, in contrast with finalization, we will need to repeat reviving
>>classloaders which have non-0 vtable marks until the process converges, and no
>>new classloaders are revived. (* in finalization, both dead and live objects in finalization
>>queue are revived, and thus the revival converges in just 1 step *).

In case you chose the finalization-like + revival way, then I don't see
any significant performance hit of multiple-step convergence!  For one
thing, you'll probably agree with me that it is quite unlikely to take
more than 1 step to converge in most cases, and the additional work in
the other cases is still quite insignificant relative to the remaining
collection work!

Etienne

-- 
Etienne M. Gagnon, Ph.D.            http://www.info2.uqam.ca/~egagnon/
SableVM:                                       http://www.sablevm.org/
SableCC:                                       http://www.sablecc.org/

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