RFR: 8240532: heap inspection prints trailing @ after name of module without version

[Lois Foltan]

On 3/4/2020 12:12 PM, Stefan Karlsson wrote:
> Hi all,
>
> Please review this patch to remove a trailing @ after module names of 
> modules without a version.
>
> https://cr.openjdk.java.net/~stefank/8240532/webrev.01/
> https://bugs.openjdk.java.net/browse/JDK-8240532
>
> The heap inspection functionality generates and prints a class histogram.
>
> Full image builds show module name and version as 'name at version':
> [3,640s][trace][gc,classhisto      ] GC(1)    4: 5067 162144  
> java.lang.String (java.base at 15-internal)
>
> Exploded builds don't have a version and prints 'name@'
> [4,361s][trace][gc,classhisto      ] GC(1)    3: 7144 228608  
> java.lang.String (java.base@)
>
> This looks weird and I propose that we drop the trailing @ when 
> there's no version string:
> [4,361s][trace][gc,classhisto      ] GC(1)    3: 7144 228608  
> java.lang.String (java.base)
>
> This affects the output of:
> * -Xlog:classhisto*=trace
> * jcmd <pid> GC.class_histogram
> * inspectheap attach operation
> * jmap -histo
>
> I've run the tests I could find that were using these operations. 
> Other than that I intend to run tier1-3.
>
> Do others agree with this change?

Yes, I think this change looks good and is consistent with how it is 
currently handled in javaClasses.cpp/print_stack_element_to_stream() and 
frame.cpp/frame::print_on_error() for example.  However, all of these 
places should really be calling ModuleEntry::should_show_version() 
instead of directly checking if the version() is NULL.  But that could 
be addressed in a differing RFE.

Thanks,
Lois

>
> Thanks,
> StefanK