RFR (M): 8022800: Use specific generations rather than generation iteration

Bengt Rutisson bengt.rutisson at oracle.com
Wed Aug 14 07:01:55 UTC 2013

Thanks Jon and Erik for reviews!

Here is an updated webrev that address some minor comments from Erik:


On 8/12/13 3:34 PM, Bengt Rutisson wrote:
> Hi everyone,
> Could I have a couple of reviews of this change?
> http://cr.openjdk.java.net/~brutisso/8022800/webrev.00/
> The interesting change is in genCollectedHeap.hpp, where I change the 
> methods prev_gen(), next_gen() and get_gen() to never return NULL. The 
> rest of the changes are ripple effects of this change.
> From the CR:
> The generations abstraction in the GC code was intended to be very 
> general. In practice we now always have exactly two generations - the 
> young and the old. This means that the GC code can be simplified quite 
> a bit.
> A first step is to change from iteration over generations to 
> explicitly specify which generation is needed. This makes the code 
> easier to follow and it also helps tools like Parfait to understand 
> the code better.
> This bug targets some simple clean-ups. A natural follow up of this is 
> probably to change the name of GenCollectedHeap to 
> TwoGenerationCollectedHeap (similar to the existing 
> TwoGenerationCollectorPolicy). But that will be handled separately.
> Thanks,
> Bengt

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