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I'm not sure what benefit you're picturing from escape analysis, but EA is largely pointless because GCs have gotten so good that stack allocation of objects is really no better than heap allocation plus collection of short-lived objects.

I worked for years on escape analysis in IBM's Java JIT compiler. We struggled to find any actual programs that showed any benefit at all. The real benefits of escape analysis were second-order effects like eliminating monitor operations on non-escaping objects, or breaking apart objects and putting their fields into registers (especially autoboxed primitives). The actual stack allocation wasn't really any faster than heap allocation, and a GC operation in the nursery doesn't even look at dead objects.

EA is basically a microbenchmark-killer. For real software, it's not often worth the trouble.




I think we're agreeing. The party line for a long time was that Java didn't have value types because they thought EA would render it unnecessary. But as you say, it never really approached being able to replace the benefits of true value types.


Ah, got it. Yes, I think that claim about EA would be considered naive in retrospect.




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