[jdom-interest] Re: New realease, Text class... Arghh

Dennis Sosnoski dms at sosnoski.com
Thu Jan 10 10:10:08 PST 2002

Short-lived object creation/recycling is one thing Sun has optimized 
heavily in Hot Spot. I've always felt that creating lots of short-lived 
object was just a sign of poorly designed code, and would rather they'd 
concentrated on other areas. They didn't ask me, though... ;-)

The issue in iterator vs indexing a linked list is that the iterator 
overhead is constant, while the indexing cost is proportional to the 
length of the list, O(n). If you're going through the entire list in 
sequence, this becomes O(n^2). If you know your lists are never going to 
have more than a few items this is fine; otherwise, you're better off 
using an Iterator.

Avoiding object creation completely is going to give the best 
performance, which is why I like having calls to access attributes and 
content directly.

  - Dennis

Alex Rosen wrote:

>>especially since object creation overhead
>>is pretty low for Hot Spot JVMs.
>Really? I was under the impression that object creation (plus the extra GC
>work that it will cause later on) is one of the slowest things a VM can do,
>even for HotSpot. I could imagine that it might be slower than accessing a
>linked list using an index, but I didn't think that it was "pretty low"
>overhead, I thought it was just the opposite.

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