RFR: 8288282: Zero-release build is broken after JDK-8279047 due to UseHeavyMonitors is read-only

[David Holmes]

On Sat, 11 Jun 2022 15:08:38 GMT, Jie Fu <jiefu at openjdk.org> wrote:

> Hi all,
> 
> Zero-release build is broken after JDK-8279047.
> After JDK-8279047, `UseHeavyMonitors` becomes read-only in PRODUCT VMs.
> 
> But for Zero, `UseHeavyMonitors` needs to be reset if `DiagnoseSyncOnValueBasedClasses != 0`.
> 
>   // If lock diagnostics is needed, always call to runtime
>   if (DiagnoseSyncOnValueBasedClasses != 0) {
>     FLAG_SET_DEFAULT(UseHeavyMonitors, true);
>   }
> 
> 
> I never hear that people would DiagnoseSyncOnValueBasedClasses with zero vms.
> So in order to expire `UseHeavyMonitors` for all PRODUCT VMs, I suggest disabling lock diagnostics for zero vms.
> 
> Thanks.
> Best regards,
> Jie

@DamonFool , sorry I missed this when expiring UseHeavyMonitors in product mode. The Zero code should have been fixed long before now. But why not make keep the diagnostics available in the debug VM?

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PR: https://git.openjdk.org/jdk/pull/9138