On Wed, 7 Jun 2023 03:37:26 GMT, SUN Guoyun <d...@openjdk.org> wrote:
>> command: make test CONF=fastdebug JTREG="VM_OPTIONS=-Xcomp"
>> TEST=gc/TestAllocHumongousFragment.java
>> error info:
>>
>> Caused by: java.lang.NullPointerException: Cannot invoke
>> "sun.util.locale.BaseLocale.getVariant()" because "base" is null
>> at java.base/java.util.Locale.forLanguageTag(Locale.java:1802)
>> at
>> java.base/sun.util.cldr.CLDRBaseLocaleDataMetaInfo.<clinit>(CLDRBaseLocaleDataMetaInfo.java:41)
>> ... 24 more
>>
>> Note that the test runs with -XX:ShenandoahGCHeuristics=aggressive
>> -XX:+ShenandoahOOMDuringEvacALot and SoftReferences are involved
>> (LocaleObjectCache uses SoftReferences, used by printf method called in
>> getRandomInstance(Utils.java:511)).
>>
>> Maybe we have to deal with the case where the getBaseLocale() return value
>> is null. the call stack is:
>>
>> at
>> java.base/sun.util.locale.LocaleObjectCache.get(LocaleObjectCache.java:64)
>> at java.base/sun.util.locale.BaseLocale.getInstance(BaseLocale.java:169)
>> at
>> java.base/sun.util.locale.InternalLocaleBuilder.getBaseLocale(InternalLocaleBuilder.java:524)
>> at java.base/java.util.Locale.forLanguageTag(Locale.java:1874)
>>
>> in LocaleObjectCache.java:64
>>
>> 62 if (key == null || newVal == null) {
>>
>> 63 // subclass must return non-null key/value object
>>
>> 64 return null; // run here
>> 65 }
>
> SUN Guoyun has updated the pull request incrementally with one additional
> commit since the last revision:
>
> 8289220: Locale.forLanguageTag throws NPE due to soft ref used in locale
> cache being cleared
In its current form the `BaseLocale.Cache.createObject` function can return
`null`; the object returned by `BaseLocale.Key.normalizeKey(key)` holds a soft
reference to locale, and by the time `getBaseLocale` is called, the reference
may be cleared.
`Key` only uses `SoftReferences` because it must not hold a reference to the
object returned by `createObject`. We could refactor `createObject` to return a
clone of the `BaseLocale` referenced by `Key`, and then `Key` would not need to
use `SoftReference`s.
That being said, the number of long-lived `BaseLocale` objects is very limited;
we only keep them in Locale, LocaleKey, and Locale.CONSTANT_LOCALES. Unless I'm
missing something, we could solve this problem by removing `BaseLocale`
caching, and improve performance at the same time.
-------------
PR Comment: https://git.openjdk.org/jdk/pull/14211#issuecomment-1580652895
