Integrated: 8255232: G1: Make G1BiasedMappedArray freeable

[Thomas Schatzl]

On Thu, 22 Oct 2020 13:47:00 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

> Hi all,
> 
>   can I have reviews for this change that makes G1BiasedMappedArray freeable?
> 
> Previously all G1BiasedMappedArray were created as unfreeable i.e. assigned to static variables. However with JDK-8253600 I need one such biased map for the full collector which is created and deleted during full GC. So the biased array should also be freed as necessary to avoid a memory leak.
> 
> The alternative would be to statically allocate that map anyway and provide it to the current G1FullCollector instance, but I do not think the single malloc call is perf sensitive compared to full collector work and there is much point in doing something more complicated at this time. In the future I hope that the young gen collector will also be extracted from G1CollectedHeap with the same need. If/when allocation of these helper data structures becomes a problem I would suggest looking into this again.
> 
> One option then could be using some ResoureArea for these things in the future.
> 
> For this change there should be no change in behavior at all.
> 
> Testing: tier1-5
> 
> Thanks,
>   Thomas

This pull request has now been integrated.

Changeset: 5c520c3f
Author:    Thomas Schatzl <tschatzl at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/5c520c3f
Stats:     35 lines in 4 files changed: 27 ins; 2 del; 6 mod

8255232: G1: Make G1BiasedMappedArray freeable

Reviewed-by: ayang, kbarrett

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PR: https://git.openjdk.java.net/jdk/pull/808