On Fri, May 16, 2008 at 6:43 PM, Aleksey Shipilev <[EMAIL PROTECTED]> wrote: > Hi, > > > On Fri, May 16, 2008 at 10:18 AM, Xiao-Feng Li <[EMAIL PROTECTED]> wrote: > > On Fri, May 16, 2008 at 1:41 PM, Aleksey Shipilev > > <[EMAIL PROTECTED]> wrote: > >> Aha, so it's literally no way to disable buffered hashcode? That means > >> identityHashCode GC helper can't be implemented as magic. > > Why not? GC helper doesn't need to include buffered hash. > Yep, I mean here that IHC magic will perform well only when object is > in young generation. Such GC helper will infer another layer of > indirection while obtaining IHC for mature object (e.g. call to GC > helper -> check -> call to VM helper -> call to native GC). On the > other hand, it should eliminate JNI stub for > VMMemoryManager.getIdentityHashCode after all. Need to experiment > more.
Most of the objects in mature space have attached hashcode. Only those objects moved in major collections and do not yet have attached hashcode before the move will use buffered hashcode. The number should be minimum in most applications, so can be dealt with in slow path. GC helpers only need to deal with fast path. Thanks, xiaofeng > Thanks, > Aleksey. > -- http://xiao-feng.blogspot.com
