RFR: 8252041: G1: Fix incorrect uses of HeapRegionManager::max_length [v4]

[Kim Barrett]

On Thu, 17 Sep 2020 07:46:25 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

>> Hi all,
>> 
>>   can I have reviews for this change that fixes some uses of HeapRegionManager::max_regions()/max_expandable_regions() in
>>   our code to use the correct variant?
>> 
>> HeapRegionManager::max_length gives the absolute maximum number of regions reserved for the heap based on the
>> reservation.
>> HeapRegionmanager::max_expandable_regions() returns the maximum number of regions the heap can grow to (can be
>> committed).
>> Typically they are exchangeable, but if the reservation is larger than what -Xmx allows (like when file-mapping old
>> gen), this is not the case, and causes assertions. In some cases the existing region manager code could (if it reserved
>> more than -Xmx) give back more than -Xmx allows.  Testing: tier1-5.
>
> Thomas Schatzl has updated the pull request incrementally with three additional commits since the last revision:
> 
>  - sjohanss review: Fix comments
>  - Merge branch '8252041-incorrect-use-of-max-length' of gh:tschatzl/jdk into 8252041-incorrect-use-of-max-length
>  - Merge branch '8252041-incorrect-use-of-max-length' of gh:tschatzl/jdk

Marked as reviewed by kbarrett (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/178