Request for review (S): 7110718 -XX:MarkSweepAlwaysCompactCount=0 crashes the JVM

[Bengt Rutisson]

Hi all,

Can I have a couple of reviews for this small change?
http://cr.openjdk.java.net/~brutisso/7110718/webrev.01/

It is a fix for the issue that Ramki reported recently. 
MarkSweepAlwaysCompactCount is used for division and Hotspot crashes if 
it is set to 0.

I choose to log an error and exit the VM if someone tries to start with 
-XX:MarkSweepAlwaysCompactCount=0. An alternative is to just log a 
warning and set it to 1.

I prefer the error way since it is not really clear what one wants to 
achieve with MarkSweepAlwaysCompactCount=0. Always do full compactions 
or never do full compactions? So I am not convinced that 1 is an 
appropriate value.

Also, since the VM, up until now, has crashed if someone tried 
-XX:MarkSweepAlwaysCompactCount=0 I think we can be sure that there are 
no customers that are running with that setting. It should be safe to 
forbid it.

CR:

7110718 -XX:MarkSweepAlwaysCompactCount=0 crashes the JVM
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7110718

Thanks,
Bengt