Request for review 6840152: JVM crashes when heavyweight monitors are used

[Coleen Phillimore]

On 2/16/2011 1:33 AM, David Holmes wrote:
> Hi Coleen,
>
> I don't see a UseHeavyWeightMonitors flag in the current source. And 
> the change in arguments.cpp refers to both UseHeavyMonitors and 
> UseFastLocking, so I'm confused about this "renaming".
>
> And I'm not sure this warning logic is quite right:
>
> +   // Turn off biased locking for locking debug mode flags
> +   if (!UseFastLocking || UseHeavyMonitors) {
> +     if (!FLAG_IS_DEFAULT(UseBiasedLocking)) {
> +       warning("Biased Locking is not supported with locking debug 
> flags");
> +     }
> +     UseBiasedLocking = false;
> +   }
>
> These FLAG macros always confuse me but surely the issue is whether 
> UseBiasedLocking is true, not whether it has its "default value" ???
>
> On some architectures the default value of UseBiasedLocking is false.

You are right.  The FLAG_IS_DEFAULT is if someone specified it on the 
command line, but I should also check if they specified it to be true.

The earlier description was replaced with:
Summary: Turn off biased locking if !UseFastLocking or UseHeavyMonitors 
options are requested.


Thanks,
Coleen

>
> David
>
>
> Coleen Phillimore said the following on 02/16/11 05:19:
>> Summary: Renamed UseHeavyWeightMonitors flag to !UseFastLocking flag 
>> and turn off biased locking if !UseFastLocking option is requested.
>>
>> open webrev at http://cr.openjdk.java.net/~coleenp/6840152/
>> bug link at http://bugs.sun.com/view_bug.do?bug_id=6840152
>>
>> Tested against specjbb2005.
>>
>> Thanks,
>> Coleen
>>