RFR: Use current time instead of DBL_MAX for immediate uncommit

[Roman Kennke]

OK

On Mon, Mar 5, 2018 at 11:08 AM, Aleksey Shipilev <shade at redhat.com> wrote:
> Found this during backports: DBL_MAX is not always trivially accessible. Let's just use current time
> for "before" argument, which does the same: uncommitting all regions that were emptied before
> current time.
>
> diff -r 3c0dbf1ed0fd src/hotspot/share/gc/shenandoah/shenandoahConcurrentThread.cpp
> --- a/src/hotspot/share/gc/shenandoah/shenandoahConcurrentThread.cpp    Fri Mar 02 22:12:34 2018 +0100
> +++ b/src/hotspot/share/gc/shenandoah/shenandoahConcurrentThread.cpp    Mon Mar 05 11:07:09 2018 +0100
> @@ -169,7 +169,7 @@
>          notify_explicit_gc_waiters();
>
>          // Explicit GC tries to uncommit everything
> -        heap->handle_heap_shrinkage(DBL_MAX);
> +        heap->handle_heap_shrinkage(os::elapsedTime());
>        }
>
>        // If this was the allocation failure GC cycle, notify waiters about it
>
> Testing: hotspot_fast_gc_shenandoah, RSS tests
>
> Thanks,
> -Aleksey
>