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

[Yumin Qi]

Hi,

   New webrev to use "-XX:+AssumMP" flag. Also add warning to recommend 
use this flag with "-XX:ParallelGCThreads" to remind user to avoid 
running with only one GC thread. This is verified by Oleksandr with the 
test case running on Linux which is not Zone configured.

   Same link.

Thanks
Yumin

On 3/20/2013 2:27 PM, Yumin Qi wrote:
>
> 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