On Sat, 6 Mar 2021 13:34:14 GMT, Claes Redestad <redes...@openjdk.org> wrote:
>> src/java.base/share/classes/java/util/Locale.java line 946:
>>
>>> 944: Locale loc = defaultDisplayLocale; // volatile read
>>> 945: if (loc == null) {
>>> 946: loc = getDisplayLocale();
>>
>> Just interesting how did you check that the performance difference is
>> because of volatile read, and not because of replacing of the switch by the
>> "if"?
>
> I started out with this variant, only removing the double volatile reads:
>
> public static Locale getDefault(Locale.Category category) {
> // do not synchronize this method - see 4071298
> Locale loc;
> switch (category) {
> case DISPLAY:
> loc = defaultDisplayLocale;
> if (loc == null) {
> synchronized(Locale.class) {
> loc = defaultDisplayLocale;
> if (loc == null) {
> loc = defaultDisplayLocale = initDefault(category);
> }
> }
> }
> return loc;
> case FORMAT:
> loc = defaultFormatLocale;
> if (loc == null) {
> synchronized(Locale.class) {
> loc = defaultFormatLocale;
> if (loc == null) {
> loc = defaultFormatLocale = initDefault(category);
> }
> }
> }
> return loc;
> default:
> assert false: "Unknown Category";
> }
> return getDefault();
> }
>
> Scores were the same:
> Benchmark Mode Cnt Score Error Units
> LocaleDefaults.getDefault avgt 5 10.045 ± 0.032 ns/op
> LocaleDefaults.getDefaultDisplay avgt 5 11.301 ± 0.053 ns/op
> LocaleDefaults.getDefaultFormat avgt 5 11.303 ± 0.054 ns/op
>
> I then refactored and checked that the refactorings were performance neutral.
And it is faster than the final version?
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PR: https://git.openjdk.java.net/jdk/pull/2845
