[Internet]Re: RFR: JDK-8306696: Remove MetaspaceReclaimPolicy=aggressive and obsolete MetaspaceReclaimPolicy [v5]

[jiefu(傅杰)]

I've made a pr for this issue: https://github.com/openjdk/jdk/pull/13714

On 2023/4/28, 20:17, "hotspot-runtime-dev on behalf of David Holmes" <hotspot-runtime-dev-retn at openjdk.org <mailto:hotspot-runtime-dev-retn at openjdk.org> on behalf of david.holmes at oracle.com <mailto:david.holmes at oracle.com>> wrote:


Thomas,


You seem to have missed fixing test:


test/hotspot/jtreg/runtime/Metaspace/elastic/TestMetaspaceAllocationMT2.java


it now fails to compile:


/System/Volumes/Data/mesos/work_dir/jib-master/install/jdk-21+21-1699/src.full/open/test/hotspot/jtreg/runtime/Metaspace/elastic/TestMetaspaceAllocationMT2.java:115: 
error: cannot find symbol
System.out.println("#### ReclaimPolicy: " + 
Settings.settings().reclaimPolicy);


^
symbol: variable reclaimPolicy
location: class Settings


We have mass failures in tiers 2 and 3.


David
-----




On 28/04/2023 4:26 pm, Thomas Stuefe wrote:
> On Thu, 27 Apr 2023 12:17:56 GMT, Thomas Stuefe <stuefe at openjdk.org <mailto:stuefe at openjdk.org>> wrote:
> 
>>> The diagnostic setting MetaspaceReclaimPolicy=aggressive is very rarely used, and I would like to remove it. This is a part of a larger effort to simplify metaspace coding and cut down on testing time, in preparation for upcoming changes to Metaspace with Lilliput.
>>>
>>> MetaspaceReclaimPolicy had recently been demoted from an official to a diagnostic switch (see CSR [JDK-8302130](https://bugs.openjdk.org/browse/JDK-8302130 <https://bugs.openjdk.org/browse/JDK-8302130>)). See also the CSR text for a more in-depth explanation of what this switch does, its history, and why it could be removed for good.
>>>
>>> The switch has not that much impact on RSS reduction but has the side effect of increasing VMA fragmentation compared to the default setting since it reduces the size of metaspace commit granules from 64K to 16K. The settings used by default (MetaspaceReclaimPolicy=balanced) are proven now in the field and can be used without alternatives (since any alternative has to be tested).
>>>
>>> Since this would remove the last valid value for MetaspaceReclaimPolicy apart from its default "balanced" value, it makes sense to deprecate MetaspaceReclaimPolicy at the same time.
>>>
>>> This allows us to cut down on Metaspace testing quite a bit since it removes one permutation from the test set.
>>
>> Thomas Stuefe has updated the pull request incrementally with one additional commit since the last revision:
>>
>> make flag obsolete
> 
> Thank you David!
> 
> -------------
> 
> PR Comment: https://git.openjdk.org/jdk/pull/13597#issuecomment-1527037367 <https://git.openjdk.org/jdk/pull/13597#issuecomment-1527037367>