RFR (S): 8058446: G1 Hot card cache should use ArrayAllocator to allocate the cache array

Mikael Gerdin mikael.gerdin at oracle.com
Tue Feb 17 16:13:14 UTC 2015


Hi Thomas,

On 2015-02-17 16:18, Thomas Schatzl wrote:
> Hi all,
>
>    can I have reviews for this small change (or feedback): it changes the
> hot card cache array that holds the hot cards from always using C heap
> to an ArrayAllocator.
>
> This is because the hot card cache may be specified to be quite large
> (up to 2^31 entries), which will result in native OOME at startup.
>
> The fix is to use an ArrayAllocator for larger hot card caches.
>
> Another potential improvement would be to decrease the maximum allowed
> HCC size to something more reasonable - however I have no idea what this
> size could be.
>
> One comment in the CR suggests to add a test that adds testing of the
> boundary values. However, I do not see how you could create a stable
> test for that, given that that test would somehow need to guess a
> maximum reasonable value to not crash on any machines.
>
> I left a test out for now as the change itself is pretty simple.
>
> A few values are already checked in the TestAuxiliaryData* tests too.
>
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8058446
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8058446/webrev/

Looks fine to me.

/Mikael

> Testing:
> jprt
>
> Thanks,
>    Thomas
>
>


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