RFR 8234270: [REDO] JDK-8204128 NMT might report incorrect numbers for Compiler area
Zhengyu Gu
zgu at redhat.com
Thu Nov 21 17:13:39 UTC 2019
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
>
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