RFR: 8221701: Archive constant BaseLocales

[naoto.sato at oracle.com]

Hi Claes,

The new version looks good, and I like this approach better. Simpler and 
easily maintainable IMO. Also I like the improved startup time, which I 
think is more important than multiple creation of Locale instances, 
which is not very common.

Naoto

On 4/2/19 3:22 PM, Claes Redestad wrote:
> Hi Naoto,
> 
> thanks for reviewing!
> 
> On 2019-04-02 17:36, Naoto Sato wrote:
>> Hi Claes,
>>
>> Thank you for looking into this. I remember we discussed this before. 
>> One comment I have is that, currently the archive map seems to have 
>> two level structure, i.e, lang, then country. There is another basic 
>> element that consists of a locale, that is script. At the moment, 
>> there is not a constant that has script in it, but if we wanted to 
>> have a constant locale, say zh-Hans, it cannot be archived. It's ok 
>> for now, but can it be extended if we want in the future, without any 
>> compatibility implications?
> 
> You're right that adding a constant with script would force a rewrite.
> One alternative solution is to not use nested maps, but instead archive
> an array of BaseLocales that we iterate over:
> 
> http://cr.openjdk.java.net/~redestad/8221701/open.01/
> 
> This has more boilerplate but is simpler in structure and I believe
> easier to maintain. This is also significantly faster on startup than
> the previous iteration (also when default Locale is not in the set of
> predefined constants).
> 
> Performance of many repeated calls to new Locale/Locale.getInstance sees
> a drop with either approach (from ~0.5us/op to ~0.7us/op on a new 
> Locale("se", "SV") micro), but I believe creation of Locale objects are
> unlikely to be on the critical path.
> 
> What do you think?
> 
> Thanks!
> 
> /Claes
> 
>>
>> Naoto
>>
>> On 4/2/19 3:14 AM, Claes Redestad wrote:
>>>
>>>
>>> On 2019-04-01 17:46, Claes Redestad wrote:
>>>> Hi,
>>>>
>>>> by archiving constant BaseLocale objects, we can simplify (and speed 
>>>> up)
>>>> creation of the constant Locale objects in java.util.Locale which are
>>>> unconditionally created during startup.
>>>>
>>>> Bug:    https://bugs.openjdk.java.net/browse/JDK-8221701
>>>> Webrev: http://cr.openjdk.java.net/~redestad/8221701/open.00/
>>>>
>>>> Testing: tier1-3, along with patches for JDK-8221723 and
>>>> JDK-8221724
>>>
>>> These RFEs have now been pushed, unblocking this RFE.
>>>
>>> /Claes