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

[Yumin Qi]

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