[11u] 2020-07-20, Bulk backports to sh/jdk11

[Roman Kennke]

Hi Aleksey,

the changes look good to me!

Thank you!
Roman


On Mon, 2020-07-20 at 11:07 +0200, Aleksey Shipilev wrote:
> 	Error verifying signature: Cannot verify message signature:
> Incorrect message format
> http://cr.openjdk.java.net/~shade/shenandoah/backports/jdk11-20200720/webrev.01/
> 
> This backports a few improvements, notably in Pacer:
>  [backport] 8248652: Shenandoah: SATB buffer handling may assume no
> forwarded objects
>  [backport] 8247367: Shenandoah: pacer should wait on lock instead of
> exponential backoff
>  [backport] 8247593: Shenandoah: should not block pacing reporters
>  [backport] 8249649: Shenandoah: provide per-cycle pacing stats
> 
> Testing: hotspot_gc_shenandoah {fastdebug,release}, tier{1,2} with
> Shenandoah (running, expecting no
> new failures)
>