[gsg]

In general you can't drop the contents of the arena on the floor in a GCed language, since you might have been wrong about those objects being short-lived (or because they are short lived, but they were allocated shortly before the young heap filled up and happen to still be alive). So tracing/copying is still necessary.

It is quite possible for objects that are expected to tenure to be allocated directly into the major heap. Many systems use various criteria to decide when this should be done. In particular it is common to allocate very large objects directly to avoid ever having to copy them.

There are also static analyses which attempt to determine which objects can be safely allocated in an arena-like way, that is, region inference. In some systems in addition to inference the programmer is given ways to specify that a given object should live within a certain region. MLkit is the usual example of such a system. Region systems don't seem to have been particularly popular, but there's still some work being done on them here and there.