RFR: 2178143: VM crashes if the number of bound CPUs changed during runtime

[harold seigel]

Hi Yumin,

I think a boolean flag would be better.   Perhaps one called something 
like "TreatAsMPSystem".  Its default would be FALSE.  This would 
simplify the checks and more reflects the purpose of the flag.

Harold


On 3/20/2013 5:27 PM, Yumin Qi wrote:
> Hi, can I have your code review of a small change?
>
> 2178143:  VM crashes if the number of bound CPUs changed during runtime.
>
> Situation: Customer first configure only one CPU online and turn 
> others offline to run java application, after java program started, 
> bring more CPUs back online. Since VM started on a single CPU, 
> os::is_MP() will return false, but after more CPUs available, OS will 
> schedule the app run on multiple CPUs, this caused SEGV in various 
> places where data consistency was broken. The solution is supply a 
> flag to assume it is running on MP, so lock is forced to be called.
>
> http://cr.openjdk.java.net/~minqi/2178143/
>
> Thanks
> Yumin