RFR(S): 8168305 GC.class_stats should not require -XX:+UnlockDiagnosticVMOptions

[Staffan Larsen]

> On 27 Oct 2016, at 11:41, Marcus Larsson <marcus.larsson at oracle.com> wrote:
> 
> Hi Staffan,
> 
> 
> On 2016-10-27 10:36, Staffan Larsen wrote:
>> All,
>> 
>> Please review this small patch to remove the requirement -XX:+UnlockDiagnosticVMOptions when running the GC.class_stats diagnostic command. Diagnostic commands are used for diagnosing problems and should not require restarting the JVM with a different command line flag if this can be avoided.
>> 
>> While fixing this I also noticed that VM.print_touched_methods said it required -XX:+UnlockDiagnosticVMOptions, while what it really required was -XX:+LogTouchedMethods (which in turn requires -XX:+UnlockDiagnosticVMOptions) so I changed the error message here. In this case I think it is ok to require a special command line flag since collecting the information comes with an overhead.
>> 
>> I have verified the fix manually and by running these tests: hotspot/test/runtime/CommandLine/PrintTouchedMethods.java hotspot/test/serviceability/sa/TestInstanceKlassSize.java hotspot/test/serviceability/sa/TestInstanceKlassSizeForInterface.java
>> 
>> bug: https://bugs.openjdk.java.net/browse/JDK-8168305
>> webrev: http://cr.openjdk.java.net/~sla/8168305/webrev.01/
> 
> The command description still mentions the flag, see
> src/share/vm/services/diagnosticCommand.hpp:389

Well spotted!

new webrev: http://cr.openjdk.java.net/~sla/8168305/webrev.02/ <http://cr.openjdk.java.net/~sla/8168305/webrev.02/>


> Apart from that this looks good to me!

Thanks.

> 
> Thanks,
> Marcus
> 
>> 
>> Thanks,
>> /Staffan

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