JMH results for IndexedLinkedList

[John Hendrikx]

I'm curious, why isn't ArrayDeque or ConcurrentLinkedDeque used instead? 
Or is there another requirement?

ArrayDeque has amortized O(1) for inserts at head and tail (and faster 
and more memory efficient than LinkedList as it doesn't use nodes).

ConcurrentLinkedDeque would be useful in the face of multiple threads 
(it uses nodes though, so won't be as fast as ArrayDeque).

--John

On 11/07/2022 11:58, Maurizio Cimadamore wrote:
>
> The implementation of the Foreign Function & Memory API uses an 
> internal custom linked list to add native resources to a "memory 
> session" abstraction (things that need to be cleaned up at a later point).
>
> Linked list is quite critical in our use case because we need 
> something that has a very fast insertion (in the head), and can scale 
> gracefully to handle multiple threads.
>
> In our case LinkedList is not good enough (because we want to deal 
> with concurrent writes ourselves) - but aside from that, note that, at 
> least looking at the numbers posted in your benchmarks, it seems that 
> prepending an element to a classic LinkedList is 10x faster than 
> ArrayList and 5x faster IndexList. Perhaps that's a case where 
> IndexList has not been fully optimized - but for prepend-heavy code 
> (and the javac compiler is another one of those), I think performance 
> of addFirst is the number to look at.
>
> As Tagir said, of course these use cases are very "niche" - and, at 
> least in my experience, deevelopers in this "niche" tend to come up 
> with ad-hoc specialized data structures anyways. So the return of 
> investment for adding another collection type in this space seems 
> relatively low.
>
> Maurizio
>
> On 09/07/2022 20:33, Tagir Valeev wrote:
>> 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 <coderodd3 at 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 <amaembo at 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 <coderodd3 at gmail.com>:
>>
>>             Data structure repo:
>>             https://github.com/coderodde/IndexedLinkedList
>>
>>             Benchmark repo:
>>             https://github.com/coderodde/IndexedLinkedListBenchmark
>>
>>             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
>>
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