RFR(S) 8206183: Possible construct EMPTY_STACK and allocation stack, etc. on first use

yumin qi yumin.qi at gmail.com
Wed Jul 11 17:18:33 UTC 2018

The changes look good to me.


On Sat, Jul 7, 2018 at 4:37 AM Zhengyu Gu <zgu at redhat.com> wrote:

> Hi,
> NMT has to workaround static initialization order issues: some of static
> objects, who allocate memory inside their constructors, may be
> initialized ahead of NMT, so NMT is forced to initialize itself early
> and risks its static objects may be reinitialized by C runtime.
> The workaround was to declare storage for the static objects as
> primitive arrays, then use placement new operator to initialize them, or
> just initialize them eagerly, if the results are constants.
> But the solution is not elegant, could break with some compilers.
> A better solution is to use "construct on First Use Idiom" pattern
> (https://isocpp.org/wiki/faq/ctors#static-init-order), cause we only
> have initialization order problems, those static objects do not have
> dependencies on other static objects, so we don't suffer from static
> deinitialization problems.
> Bug: https://bugs.openjdk.java.net/browse/JDK-8206183
> Webrev: http://cr.openjdk.java.net/~zgu/8206183/webrev.00/
> Test:
>    hotspot_nmt on Linux 64 (fastdebug and release)
>    Submit-test.
> Thanks,
> -Zhengyu

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