On 7/10/22 8:25 AM, Tagir Valeev wrote:
Hello!
On Sun, Jul 10, 2022 at 6:33 AM Rodion Efremov <codero...@gmail.com> wrote:
I am interested in
https://bugs.openjdk.org/browse/JDK-8143850
Is there a way for becoming an assignee for the above issue? If yes, how do I
proceed and what is the schedule?
Stuart Marks might be the right person to ask. Adding to CC.
Thanks Tagir.
There is already a considerable implementation overlap between ArrayList and
ArrayDeque that seems difficult to unify. I'm loathe to add yet another data
structure implementation that's functionally similar to the existing ones but has a
bunch of subtle performance and usage tradeoffs. Doing this would add to the
maintenance cost of the JDK and also make it more difficult for programmers to
choose the "right" data structure for their application.
Already there is a problem with ArrayList and ArrayDeque being separate classes.
ArrayDeque "fixes" the performance problem with addition/removal at the front of an
ArrayList; yet last time I checked, ArrayDeque was used only about 1% as frequently
as ArrayList. Maybe this is because people don't know about it, or maybe because
people are uncomfortable losing List-like indexed access with ArrayDeque.
Regarding JDK-8143850 there is a twisty maze through the constraints of avoiding
adding too much code, avoiding too much API surface area, and maintaining
performance. I have a prototype of ArrayList that makes it double-ended, which seems
promising, to me at least. (This is independent of SequencedCollection --
JDK-8266572 -- which is an API move, not an implementation move.) But doing this
necessarily slows down append-only operations, while providing a performance boon
for operations at the front for all but the smallest lists. The tradeoffs here are
quite subtle.
In any case I think the best path forward for "new" data structures with interesting
performance characteristics is to publish an artifact on Maven central. This will
allow people who have specialized performance needs to use it.
s'marks
With best regards,
Tagir Valeev.
Best regards,
rodde
la 9.7.2022 klo 22.33 Tagir Valeev <amae...@gmail.com> kirjoitti:
Note that nobody these days cares about LinkedList. Use-cases where LinkedList
outperforms careful use of ArrayList or ArrayDeque are next to none. So saying
that your data structure is better than LinkedList is totally not a reason to
add it to JDK. It should be better than ArrayList and ArrayDeque.
Having a single data structure that provides list and deque interface is a
reasonable idea. However it would be much simpler to retrofit existing data
structure like ArrayDeque, rather than create a new data structure. Here's an
issue for this:
https://bugs.openjdk.org/browse/JDK-8143850
There were also discussions to enhance collections in general, adding more
useful methods like getFirst() or removeLast() to ArrayList, etc. See for
details:
https://bugs.openjdk.org/browse/JDK-8266572
To conclude, the idea of adding one more collection implementation looks
questionable to me. It will add more confusion when people need to select which
collection fits their needs better. It will require more learning. This could
be justified if there are clear benefits in using it in real world problems,
compared to existing collections. But so far I don't see the examples of such
problems.
With best regards,
Tagir Valeev
сб, 9 июл. 2022 г., 11:22 Rodion Efremov <codero...@gmail.com>:
Hello,
My benchmarking suggests, that, if nothing else, my IndexedLinkedList outperforms
gracefully the java.util.LinkedList, so the use case should be the same (List<E> +
Deque<E> -interfaces) for both of the aforementioned data structures.
Best regards,
rodde
On Sat, Jul 9, 2022 at 11:19 AM Tagir Valeev <amae...@gmail.com> wrote:
Hello!
Are there real world problems/use cases where IndexedLinkedList would be
preferred in terms of CPU/memory usage over ArrayList?
сб, 9 июл. 2022 г., 07:18 Rodion Efremov <codero...@gmail.com>:
Data structure repo:
https://urldefense.com/v3/__https://github.com/coderodde/IndexedLinkedList__;!!ACWV5N9M2RV99hQ!LBLiZkI0ZS8UoU_DXtnXCXGFsFzBUd3q7qyok0L3vUbTQXbnDnXoyb8GsZUyyt2pnCjra9VSKVLJG8h-$
Benchmark repo:
https://urldefense.com/v3/__https://github.com/coderodde/IndexedLinkedListBenchmark__;!!ACWV5N9M2RV99hQ!LBLiZkI0ZS8UoU_DXtnXCXGFsFzBUd3q7qyok0L3vUbTQXbnDnXoyb8GsZUyyt2pnCjra9VSKafWnZNi$
I have profiled my data structure and it seems it’s more performant than
java.util.LinkedList or TreeList, if nothing else.
So, is there any chance of including IndexedLinkedList to JDK?
Best regards,
rodde
