On Thu, 2 Dec 2021 16:22:02 GMT, Roman Kennke <[email protected]> wrote:
>> The caches in ObjectStreamClass basically map WeakReference<Class> to
>> SoftReference<ObjectStreamClass>, where the ObjectStreamClass also
>> references the same Class. That means that the cache entry, and thus the
>> class and its class-loader, will not get reclaimed, unless the GC determines
>> that memory pressure is very high.
>>
>> However, this seems bogus, because that unnecessarily keeps ClassLoaders and
>> all its classes alive much longer than necessary: as soon as a ClassLoader
>> (and all its classes) become unreachable, there is no point in retaining the
>> stuff in OSC's caches.
>>
>> The proposed change is to use WeakReference instead of SoftReference for the
>> values in caches.
>>
>> Testing:
>> - [x] tier1
>> - [x] tier2
>> - [x] tier3
>> - [ ] tier4
>
> Roman Kennke has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Remove unnecessary import
Changes requested by plevart (Reviewer).
src/java.base/share/classes/java/io/ClassCache.java line 63:
> 61: protected SoftReference<T> computeValue(Class<?> type) {
> 62: return new
> SoftReference<>(ClassCache.this.computeValue(type), queue);
> 63: }
How does this work? You create a bare SoftReference here and register it with
queue....
...then down in processQueue() you pick it up and cast to CacheRef... Doesn't
this throw ClassCastException ?
src/java.base/share/classes/java/io/ClassCache.java line 85:
> 83: CacheRef<? extends T> cacheRef = (CacheRef<? extends T>)ref;
> 84: map.remove(cacheRef.getType());
> 85: }
See the cast to CacheRef here?
-------------
PR: https://git.openjdk.java.net/jdk/pull/6375
