RFR: 8232594: Make the output of the JFR command duration more user friendly

[Chihiro Ito]

Hi Erik,

Thank you for giving the idea and implementing unit tests.
This is good for me.

I will improve according to this idea.

Regards,
Chihiro

2019年11月8日(金) 2:39 Erik Gahlin <erik.gahlin at oracle.com>:

> Hi Chihiro,
>
> Markus and I discussed what would be a suitable format and this is what we
> came up with:
>
> - A duration of 0 is displayed as "0 s"
> - A duration less than 1 second is displayed in ms with 3 significant
> digits.
> - A duration between 1 second and 60 seconds is displayed in s with three
> significant units
> - A duration of 60 second or more uses a combination of two units, for
> example "1 m 30 s" or "3 h 30 m"
> - The maxmim unit is a day.
>
> I wrote a unit tests that you can use. Hopefully it is correct.
>
> http://cr.openjdk.java.net/~egahlin/8232594/
>
> Thanks
> Erik
>
> On 2019-10-31 15:47, Chihiro Ito wrote:
>
> Hi Erik,
>
> I can't imagine one event lasting more than a day.
> Therefore, I think the number of days is unnecessary.
> I also think we don't need duration as detailed as ns.
>
> So how about using 0.001 ms to hours?
>
> Also, it would be difficult to see all the units displayed.
> About rounding, how about using up to 3 units?
>
> For example:
> 27 h 34 m 56 s
> 34 m 56 s 789 ms
> 56 s 789.012 ms
> 789.012 ms
>
> Regards,
> Chihiro
>
>
> 2019年10月30日(水) 2:57 Erik Gahlin <erik.gahlin at oracle.com>:
>
>> Hi Chihiro,
>>
>> I don't think 1 day is a good representation of for example 27 hours.
>> The precision is too low.  I also think numbers should be rounded up
>> where applicable.
>>
>> When a duration is short, it is often convenient to use ms (with some
>> fractions) instead of microseconds. It makes it easier to compare
>> values. This is especially true if you are looking at multiple values
>> and want to compare them, for example GC pause time.
>>
>> It is probably a good idea to first decide how values should be
>> formatted before attempting an implementation.
>>
>> Erik
>>
>> > Hi,
>> >
>> > I tried to implement this to output an accurate time duration.
>> > Could you review this, please?
>> >
>> > Is a rounded duration better than an exact duration?
>> >
>> > JBS https://bugs.openjdk.java.net/browse/JDK-8232594
>> > webrev http://cr.openjdk.java.net/~cito/JDK-8232594/webrev.00/
>> >
>> > Regards,
>> > Chihiro
>>
>>