On Sat, 6 Mar 2021 05:51:17 GMT, Sergey Bylokhov <s...@openjdk.org> wrote:
>> Claes Redestad has updated the pull request incrementally with one
>> additional commit since the last revision:
>>
>> Fix omitted synchronized
>
> 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.
-------------
PR: https://git.openjdk.java.net/jdk/pull/2845
