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

[Zhengyu Gu]

Thanks, Yumin.

-Zhengyu

On 07/11/2018 01:18 PM, yumin qi wrote:
> The changes look good to me.
> 
> Thanks
> Yumin
> 
> On Sat, Jul 7, 2018 at 4:37 AM Zhengyu Gu <zgu at redhat.com 
> <mailto: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
>