RFR 8234270: [REDO] JDK-8204128 NMT might report incorrect numbers for Compiler area

[Zhengyu Gu]

Thanks, Yumin

-Zhengyu

On 11/21/19 12:12 PM, yumin qi wrote:
> Hi, Zhengyu
> 
>    The fix looks good to me.
> 
> Thanks
> Yumin
> 
> 
> 
> On Wed, Nov 20, 2019 at 5:49 AM Zhengyu Gu <zgu at redhat.com 
> <mailto:zgu at redhat.com>> wrote:
> 
>     JDK-8204128 did not fix the original bug. But new assertion helped to
>     catch the problem, as it consistently failed in Oracle internal tests.
> 
>     The root cause is that, when NMT biases a resource area to compiler, it
>     did not adjust tracking data to reflect that. When the biased resource
>     area is released, there is a possibility that its size is greater than
>     total size recorded, and underflow a size_t counter.
> 
>     JDK-8204128 patch also missed a long to ssize_t parameter type change,
>     that resulted new test failure on Windows, because long is 4-bytes on
>     Windows.
> 
>     Many thanks to Leonid Mesnik, who helped to run this patch through
>     Oracle's internal stress tests.
> 
>     Bug: https://bugs.openjdk.java.net/browse/JDK-8234270
>     Webrev: http://cr.openjdk.java.net/~zgu/JDK-8234270/webrev.00/index.html
> 
> 
>     Test:
>         hotspot_nmt
>         Submit test
>         Oracle internal stress tests.
> 
> 
>     Thanks,
> 
>     -Zhengyu
>