RFR: Fix ShenandoahFullGC worker stats handling

[Zhengyu Gu]

On Wed, 1 Sep 2021 10:24:51 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Current Windows builds fail like this:
> 
> 
> c:\buildbot\worker\build-shenandoah-jdkx-windows\build\src\hotspot\share\gc\shenandoah\shenandoahFullGC.cpp(1074): error C2131: expression did not evaluate to a constant
> c:\buildbot\worker\build-shenandoah-jdkx-windows\build\src\hotspot\share\gc\shenandoah\shenandoahFullGC.cpp(1074): note: failure was caused by a read of a variable outside its lifetime
> c:\buildbot\worker\build-shenandoah-jdkx-windows\build\src\hotspot\share\gc\shenandoah\shenandoahFullGC.cpp(1074): note: see usage of 'num_workers'
> c:\buildbot\worker\build-shenandoah-jdkx-windows\build\src\hotspot\share\gc\shenandoah\shenandoahFullGC.cpp(1075): error C2131: expression did not evaluate to a constant
> c:\buildbot\worker\build-shenandoah-jdkx-windows\build\src\hotspot\share\gc\shenandoah\shenandoahFullGC.cpp(1075): note: failure was caused by a read of a variable outside its lifetime
> c:\buildbot\worker\build-shenandoah-jdkx-windows\build\src\hotspot\share\gc\shenandoah\shenandoahFullGC.cpp(1075): note: see usage of 'num_workers'
> make[3]: *** [lib/CompileJvm.gmk:143: /cygdrive/c/buildbot/worker/build-shenandoah-jdkx-windows/build/build/windows-x86_64-server-fastdebug/hotspot/variant-server/libjvm/objs/shenandoahFullGC.obj] Error 1
> 
> 
> Instead of doing auto-alloc with worker count that is unknown at compile time, use resource area for allocations.
> 
> Additional testing:
>  - [x] Linux x86_64 `hotspot_gc_shenandoah`
>  - [x] Windows x86_64 build

Good to me.

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Marked as reviewed by zgu (Committer).

PR: https://git.openjdk.java.net/shenandoah/pull/62