Am 09.03.2010 20:18, schrieb Martin Buchholz:
On Tue, Mar 9, 2010 at 03:59, Ulf Zibis<ulf.zi...@gmx.de> wrote:
In PriorityQueue:
let's result newCapacity in 0xFFFF.FFFC =-4
then "if (newCapacity - MAX_ARRAY_SIZE> 0)" ---> false
then Arrays.copyOf(queue, newCapacity) ---> ArrayIndexOutOfBoundsException
How could newCapacity ever become -4?
Since growth is by 50%.
Oops, I must admit, that I didn't evaluate that.
Many tricks are interwoven here at one place.
I think, those magic should be better commented. Isn't PriorityQueue a
public API, visible to everybody?
As said, I think Hotspot compiler would be the better place to optimize
those if...else branches.
But even 100% looks safe...
Hm, having oldCapacity = 0x7FFF.FFFE + 100 % makes 0xFFFF.FFFC
Am I wrong ?
2.) Why don't you prefer a system-wide constant for MAX_ARRAY_SIZE ???
This should never become a public API - it's a bug in the VM.
I prefer the duplication of code to creating a new external dependency.
Good use case for new super package facility.
I can sympathise your reserve. On the other hand ...
- if there is a limit, developers should have a chance, to evaluate
against it to avoid OutOfMemoryError.
- maybe other VM's have a other/much lower limit, e.g. on small mobile
systems.
- If the bug would be fixed, who takes care about the "garbage
collection" in the code base?
- There is many public stuff in sun.misc.VM class, why not
MAX_ARRAY_SIZE/maxArraySize()?
-Ulf
