(urgent) RFR: 8148771: os::active_processor_count() returns garbage which causes VM to crash

[Kim Barrett]

> On Feb 1, 2016, at 7:51 PM, David Holmes <david.holmes at oracle.com> wrote:
> 
> This is a backout of the fix for JDK-8147906 which changes the GC to use active_processor_count() during initialization. Some systems with aggressive power management can report continually varying numbers of available processors, via sched_getaffinity, and it seems the GC code can not tolerate that. So we hg backout JDK-8147906 and revert to using processor_count() again. We will then look at how to address this going forward.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8148771
> 
> webrev http://cr.openjdk.java.net/~dholmes/8148771/webrev/
> 
> Thanks,
> David

Looks good.