RFR 8204128: NMT might report incorrect numbers for Compiler area

[Thomas Stüfe]

Hi Zhengyu,

wouldn't ssize_t not be a better choice?

Other than that, looks good.

..Thomas

On Fri, Nov 15, 2019 at 4:08 PM Zhengyu Gu <zgu at redhat.com> wrote:

> I could not reproduce the problem stated in CR.
>
> The theory is that, when releasing a 2GB+ arena,
> Arena::set_size_in_bytes() passes a negative long integer to NMT, when
> it goes through long -> int -> long conversion, at the end, it becomes a
> positive number.
>
> This problem is illustrated in new test. Without the fix, after
> releasing a 2GB+ arena, NMT shows the arena size doubled, instead of
> going down.
>
> I am not completely sure this fixes the problem reported, but it is
> worth to cleanup inconsistent types in NMT API.
>
>
> Bug: http://cr.openjdk.java.net/~zgu/JDK-8204128/webrev.00/index.html
> Webrev: http://cr.openjdk.java.net/~zgu/JDK-8204128/webrev.00/index.html
>
> Test:
>    hotspot_nmt + new test (fastdebug and release)
>    on Linux x86_64
>
> Thanks,
>
> -Zhengyu
>
>