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https://issues.apache.org/jira/browse/OFBIZ-6298?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14510954#comment-14510954 ]
Ron Wheeler commented on OFBIZ-6298:
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Since Java 7 is coming to EOL, this might be a good time to consider how the Java 8 Stream processing will be used under the various scenarios being discussed around the choice of underlying collection structure.
This also affects some of the performance discussion since Streams take advantage of multi-core CPUs to process collections in parallel.
> Java collection use optimized
> -----------------------------
>
> Key: OFBIZ-6298
> URL:
https://issues.apache.org/jira/browse/OFBIZ-6298> Project: OFBiz
> Issue Type: Improvement
> Components: ALL COMPONENTS
> Affects Versions: Trunk
> Reporter: Nicolas Malin
> Assignee: Nicolas Malin
> Priority: Minor
> Labels: collection, performance
>
> With the javolution collection cleaning (OFBIZ-5169,OFBIZ-5781) , we need to realize a second pass to control what instantiation would be better.
> For List between LinkedList, ArrayList
> {quote}
> Using ArrayList, rather than LinkedList, as a default is a good approach because ArrayList will work better in most situations (in terms of algorithmic runtimes and memory footprints).
> However I think it is important to wisely choose ArrayList or LinkedList based on the context, because sometimes a linked list may be a better choice: I am not saying we should do it now and we can tackle this at a later moment, possibly focusing only on list that can be very big and analyzing their usage to see if array or linked list is better; it would be also nice, when we use ArrayList, to see if we can predict the capacity of the list and allocate it at creation: if we can do this we will have a more predictable memory usage and less unpredictable peaks under heavy load (when the array capacity is reached and the array is copied to a new one with double capacity).
> {quote}
> more documentation on :
> *
https://docs.oracle.com/javase/tutorial/collections/implementations/list.html> *
http://stackoverflow.com/questions/322715/when-to-use-linkedlist-over-arraylist> For Map between HashMap and LinkedHashMap :
> {quote}
> Javolution Map Iterators return items in insertion sequence (HashMap does not), so any code relying on the original insertion order must use a LinkedHashMap.
> {quote}
> *
http://stackoverflow.com/questions/2889777/difference-between-hashmap-linkedhashmap-and-treemap> If you detect an optimization, please comments this issues
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