hg: jdk8/tl/jdk: 7145454: JVM wide monitor lock in Currency.getInstance(String)

[Naoto Sato]

Hi David,

Sorry, the review was done in the i18n team and did not go to core libs 
alias.

In your suggested fix, I think there is a very slight chance that two 
threads could get different Currency instances if the first thread was 
interrupted just after instantiating "currencyVal" instance, which has 
not been the case in the prior implementation. Although returning the 
singleton instance is not mandated by the spec, I though it is safer to 
keep the same behavior and that get() cost is almost negligible.

Naoto

On 3/21/12 7:27 P, David Holmes wrote:
> Hi,
>
> I'm sorry I missed the review of this change. The following is somewhat
> inefficient:
>
> instance = instances.putIfAbsent(currencyCode,
> new Currency(currencyCode, defaultFractionDigits, numericCode));
> return (instance != null ? instance : instances.get(currencyCode));
>
> If the putIfAbsent succeeds then the value to return is the newly
> constructed Currency instance. So if we track that object then we don't
> need to do the additional get():
>
> Currency currencyVal =
> new Currency(currencyCode, defaultFractionDigits, numericCode);
> instance = instances.putIfAbsent(currencyCode, currencyVal);
> return (instance != null ? instance : currencyVal);
>
> Cheers,
> David
>
>
> On 22/03/2012 3:12 AM, naoto.sato at oracle.com wrote:
>> Changeset: 4a5817f9e249
>> Author: naoto
>> Date: 2012-03-21 10:10 -0700
>> URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/4a5817f9e249
>>
>> 7145454: JVM wide monitor lock in Currency.getInstance(String)
>> Reviewed-by: okutsu
>>
>> ! src/share/classes/java/util/Currency.java
>>