RFR: JDK-8293114: JVM should trim the native heap [v4]

[Thomas Stuefe]

On Fri, 7 Jul 2023 04:42:53 GMT, David Holmes <dholmes at openjdk.org> wrote:

> I had an initial look at this. Seems okay in principle. The naming/terminology needs some updating IMO: "trimNative" doesn't convey enough information, please use "trimNativeHeap". "trim" for logging tag is also too non-descript.
> 
> As this is initially experimental I'm not overly concerned about the impact, though I do cringe at yet-another-VM-thread.
> 
> FYI I will be away until next Thursday, but no need to wait for me for further comments.

Thank you @dholmes-ora. 

I dislike the introduction of another thread too, but the benefits are undeniably there, and we need  to keep the invocation of malloc_trim away from other code paths. That said, maybe a future glibc will offer us a ways to influence trim to make its runtime predictable. Which would remove the need of an own thread.

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PR Comment: https://git.openjdk.org/jdk/pull/14781#issuecomment-1625271681