5 ms·
The Java link doesn't describe a way to have a pointer to a subobject. In Java you must always point at the start of an object. In Go, objects are segregated
by ErikCorry 4y ago
The Java link doesn't describe a way to have a pointer to a subobject. In Java you must always point at the start of an object.
In Go, objects are segregated by allocation size, so the GC can round subobject pointers to keep the surrounding object alive.
- aardvark179 4y agoAlthough it isn't visible from the language level the JVM internally does have "derived pointers" which are normally stored on the stack and point to an offset within an object. The GC can figure this out because it has a map for what the stack entries mean.
- moonchild 4y ago'The' JVM can internally have whatever it likes; so long as it is not exposed at the language level, nothing prevents an implementation from being devised which does not have such things internally, and which has a treadmill.
- pjmlp 4y agoJNI and Unsafe also exist, it isn't only about the language alone.
- ErikCorry 4y agoOh cool, I didn't realize the stack maps were so advanced. Now I'm trying to imagine which optimizations made this necessary/useful.