RFR(xxs): 8251257: NMT: jcmd VM.native_memory scale=1 crashes target VM
David Holmes
david.holmes at oracle.com
Sun Aug 9 06:28:59 UTC 2020
On 9/08/2020 1:01 am, Thomas Stüfe wrote:
> Hi David,
>
> On Sat, Aug 8, 2020 at 2:32 PM David Holmes <david.holmes at oracle.com
> <mailto:david.holmes at oracle.com>> wrote:
>
> Hi Thomas,
>
> Wouldn't a scale name of "b" be more appropriate given the
> acceptance of
> "scale=b"? It seems weird to me that scale=1 is even accepted in the
> first place.
>
>
> I am not sure what you refer to, the added case in the switch construct?
Yes. I expected to see
37 switch(scale) {
38 case B: return "B";
39 case K: return "KB";
40 case M: return "MB";
41 case G: return "GB";
42 }
...
> If yes, this is the string of the unit NMT prints its numbers with. For
> byte sizes, we normally omit the unit, so I do it here too.
... but if the convention is to omit the unit for bytes then that is
fine. The use of "1" in the switch rather than B made this look even
odder to me. And I recognise that for some reason the code uses the
alias "1" instead of "B" as the primary way to refer to the "byte" scale.
> If you object against the name of the scale as used in the scale
> argument, that has been there before and changing it is not subject of
> the patch. I just don't want the target VM to crash.
Sorry I didn't intend to suggest that you change it, just commenting
that it seems quite odd to me and inconsistent with the other scale values.
>
> And can you please add some information to the bug report.
>
>
> Done. I thought subject + assert printout would be sufficient, sorry for
> the brevity.
Thanks.
David
> Thanks,
> David
>
>
> Thank you, Thomas
>
>
> On 8/08/2020 4:15 pm, Thomas Stüfe wrote:
> > Hi,
> >
> > may I have a second Review please?
> >
> > All tests at SAP went through successfully, as did the jdk-submit
> tests at
> > Oracle.
> >
> > Thanks!
> >
> > ..Thomas
> >
> > On Thu, Aug 6, 2020 at 5:07 PM Thomas Stüfe
> <thomas.stuefe at gmail.com <mailto:thomas.stuefe at gmail.com>> wrote:
> >
> >> Hi,
> >>
> >> very simple small fix.
> >>
> >> jcmd VM.native_memory allows for scale=1 to print exact byte
> values, but
> >> crashes when printing.
> >>
> >> JBS: https://bugs.openjdk.java.net/browse/JDK-8251257
> >> webrev:
> >>
> http://cr.openjdk.java.net/~stuefe/webrevs/8251257-nmt-scale-1-crash/webrev.00/webrev/
> >>
> >> Thanks, Thomas
> >>
>
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