Java performs escape analysis and may allocate non-escaping objects on the stack.
> Moving objects from the heap to the stack
> Many sources report that escape analysis moves Java objects from the heap to the stack. As Aleksey Shipilёv points out in his article about scalar replacement, the JVM does not do this implementation. It's just a misconception. But it's an interesting one, and I wonder why the JVM doesn't implement it.
In my defence the sentence I quoted isn't so much deliberately misleading, as outright false. It essentially states that 'new' always results in a heap allocation, which just isn't true.
A profoundly unhelpful writing style, going out of its way to punish skim-readers. I'm reminded of this TV Tropes page: http://tvtropes.org/pmwiki/pmwiki.php/Main/ByNoIMeanYes
From that article:
> Java doesn't store any object in the stack. It does store local variables on the stack: primitive types like int or boolean. It also store the pointers to objects on the stack. But it doesn't store the objects themselves on the stack. Anything you create with new is always created on the heap.
Is that true? For years now there have been articles from serious sources discussing JVM escape-analysis-based optimisations.
Is there something mistaken in the analysis in this DZone article?
https://dzone.com/articles/do-not-let-your-java-objects-esca...
How about this StackOverflow answer, which even goes into the detail of distinguishing escape-analysis, stack allocation of objects, and object deconstruction+scalar replacement:
If stack allocation was really done, it would allocate the entire object storage on the stack, including the header and the fields, and reference it in the generated code. The caveat in this scheme is that once the object is escaping, we would need to copy the entire object block from the stack to the heap, because we cannot be sure current thread stays in the method and keeps this part of the stack holding the object alive. Which means we have to intercept stores to the heap, in case we ever store stack-allocated object — that is, do the GC write barrier.