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

[Yumin Qi]

Hi, Harold

   Thought about that, but did not use that way since future plan may 
rely on the value supplied such as GC Threads mentioned in the bug.

Thanks
Yumin

On 3/20/2013 3:13 PM, harold seigel wrote:
> 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
>