RFR: JDK-8280940: gtest os.release_multi_mappings_vm is racy [v2]

[Thomas Stuefe]

On Wed, 9 Feb 2022 08:17:43 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Okay, https://bugs.openjdk.java.net/browse/JDK-8263464 is still a problem. This means that even though we can release multiple mappings with os::release_memory, NMT cannot cope with that.
>> 
>> AFAIK the only real example of releasing multiple segments in one go is Windows + UseNUMA, and there os::release_memory(), when called over multiple segments, just recursively releases the segments individually. So I believe this works with NMT. Still, it would be nice to fix this.
>> 
>> @zhengyu123 : do you think https://bugs.openjdk.java.net/browse/JDK-8263464 is difficult to fix? Should I take a stab at it or do you want to take a look?
>
> There used to not be a way to run gtests with non-default -XX:whatever
> arguments and the like. But it looks like you did something about that in
> JDK-8251158. I had no idea!

:) thanks. Yes, I was afraid of missing out on tests. Since then, we have embraced this pattern of XX-specific gtests. It's a nice way to get test coverage with not much effort.

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PR: https://git.openjdk.java.net/jdk/pull/7288