RFR (XXS): 8156660: JDK-8150393 does not set _scan_in_progress properly

[Erik Helin]

On 2016-05-10, Thomas Schatzl wrote:
> Hi all,
> 
>   could I have reviews for this bug introduced in JDK-8150393 that
> unconditionally sets G1CMRootRegions::_scan_in_progress to true when
> preparing for root region scan?
> 
> The change causes some perf issue (since we are starting up threads
> doing nothing), but with JDK-8155810 this causes a guarantee to fail (I
> noticed this issue when testing JDK-8155810).
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8156660
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8156660/webrev

Looks good, Reviewed.

Thanks,
Erik

> Testing:
> jprt (running), local testing
> 
> Thanks,
>   Thomas