RFR (XS) 8222818: NMT summary could show the GC in use

[David Holmes]

Hi Eric,

On 23/04/2019 8:13 am, Eric Caspole wrote:
> Hi, could I have reviews and any opinions on this little change to show 
> the GC name in the NMT output, as this helps us to more easily triage 
> performance data.

The idea seems fine.

For the implementation wouldn't it be simpler to do something like:

if (flag == mtGC) {
   out->print("%s - %s (", NMTUtil::flag_to_name(flag),
                           GCConfig::hs_err_name());
} else {
   out->print("-%26s (", NMTUtil::flag_to_name(flag));
}

and skip the need for a local buffer and snprintf?

Aside: it's probably used in enough different contexts that 
GCConfig::hs_err_name should be renamed.

Also if the VM terminates during initialization is it possible for this 
code to be executed before the GCConfig has been setup? And if so how 
will it behave?

Thanks,
David

> This passed tier 1 and 2.
> Thanks,
> Eric
> 
> 
> JBS:
> https://bugs.openjdk.java.net/browse/JDK-8222818
> 
> webrev:
> http://cr.openjdk.java.net/~ecaspole/JDK-8222818/02/webrev/