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https://issues.apache.org/jira/browse/FLEX-33341?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13545570#comment-13545570
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Michael Labriola commented on FLEX-33341:
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The iterative slow down is IMO the test harness and not the VectorCollection.
The confusion comes from the difference in these two collection types.
To have any sort of typed data (as we don't have generics in AS), you pass a
Vector into the VectorCollection to be used. The ArrayCollection makes its own
Array. This means they are on roughly equal ground for the first test.
However, in the test harness, the second to last test filters both of these
collections down to 1 item. Then calls removeAll(). A little known and
interesting feature of ListCollectionView is that removeAll() only removes the
items currently in the view if the view is filtered... meaning in both cases, 1
item is removed and leaves the other 49999.
When the test is run again, a new ArrayCollection (and hence a new Array) is
created, but the actual backing Vector to the VectorCollection is reused... and
it still has nearly 50000 items in it.
---
Now, regarding the actual performance we might be able to squeeze some more out
but here is the core issue. VectorCollection needs to be a ListCollectionView
extension in order to work in all of the Flex components. ListCollectionView
uses an Array internally for all its indexes and then manages an IList,
implemented by either an ArrayList or a VectorList. So, that is the only part
that really gets to be Vector versus Array. So, the things that would most
benefit from being a Vector (index and retrieval) aren't and the things that
are least favorable to use Vector are...
That is not to say that more can't be done, but the initial goal with
VectorCollection was to provide the ability to use existing Vectors that are
accessed throughout the application within Flex components.
Unfortunately the way ListCollectionView interacts with IList it removes many
of the benefits of Vector. The real answer here IMO is to change
ListCollectionView and places that reference the implementation directly, to
ensure we could remake VectorCollection without extending ListCollectionView or
to rework ListCollectionView to use Vectors internally. Then we would see real
performance benefits on both ArrayCollection and VectorCollection.
So, IMO, this is a performance issue that can be addressed with some
architectural changes but not a bug.
Mike
> VectorCollection becomes progressively slower
> ---------------------------------------------
>
> Key: FLEX-33341
> URL: https://issues.apache.org/jira/browse/FLEX-33341
> Project: Apache Flex
> Issue Type: Bug
> Components: Collections
> Affects Versions: Apache Flex 4.9.0
> Environment: Flash Player 11.5
> Reporter: Simon Gladman
> Labels: VectorCollection
> Fix For: Apache Flex 4.9.0
>
>
> If I repeatedly addItem() and removeAll() from a VectorCollection, the
> removeAll() and refresh() methods become progressively slower.
> An example can be found here:
> http://flexmonkey.blogspot.co.uk/2013/01/apache-flex-490-vectorcollection-vs.html
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