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

David Holmes David.Holmes at
Tue Feb 15 22:33:20 PST 2011

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.


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
> bug link at
> Tested against specjbb2005.
> Thanks,
> Coleen

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