Caches violate the generational hypothesis. Entries die in middle age: long enough to have survived multiple young generation collections, so that they are prom

Caches violate the generational hypothesis. Entries die in middle age: long enough to have survived multiple young generation collections, so that they are promoted to older generations. The problem is that older generations are (a) not collected as frequently, (b) are often larger than newer generations, and (c) have a lower proportion of dead space to live objects, so the effort of tracing has lower value. Caches that are in scalar data forms (e.g. byte arrays) or off-heap aren't too bad - bytes and off-heap memory doesn't need to be traced. If you're caching an object graph dense with pointers, then not so great.