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https://issues.apache.org/jira/browse/XMLBEANS-389?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12663994#action_12663994
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Radu Preotiuc-Pietro commented on XMLBEANS-389:
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The reason AbstractList.modCount cannot be used is that there could be
modifications to the document coming from outside of the List implementation
(unlike an ordinary ArrayList). That code can't know how many Iterators are
currently opened on the same section of the document and can be affected by the
change.
I agree that this limitation has to be documented somewhere.
> List accessors generated with -javasource=1.5 produce lists that scale poorly
> with the size of the list
> -------------------------------------------------------------------------------------------------------
>
> Key: XMLBEANS-389
> URL: https://issues.apache.org/jira/browse/XMLBEANS-389
> Project: XMLBeans
> Issue Type: Bug
> Components: Compiler
> Affects Versions: Version 2, Version 2.1, Version 2.2, Version 2.2.1,
> Version 2.3, Version 2.3.1, Version 2.4 , Version 2.4.1
> Reporter: Philip Aston
> Attachments: testcase.tgz
>
>
> When a schema is compiled with -javasource=1.5, convenient list based
> accessors are generated as well as the array accessors. E.g.
> java.util.List<java.lang.String> getParamList()
> The implementation of the List is built upon java.lang.AbstractList. The
> AbstractList iterator's hasNext() method calls size(). For an XMLBean
> generated list, size() walks the store and so iteration scales quadratically.
> Here are some numbers showing the problem:
> XMLBeans backed list of 1 strings: 0.013766 ms
> XMLBeans backed list of 16 strings: 0.255458 ms
> XMLBeans backed list of 256 strings: 1.612057 ms
> XMLBeans backed list of 1024 strings: 25.458934 ms
> XMLBeans backed list of 2048 strings: 123.393447 ms
> XMLBeans backed list of 4096 strings: 505.594661 ms
> plain list of 1 strings: 0.002304 ms
> plain list of 16 strings: 0.007788 ms
> plain list of 256 strings: 0.013384 ms
> plain list of 1024 strings: 0.052215 ms
> plain list of 2048 strings: 0.103550 ms
> plain list of 4096 strings: 0.206648 ms
> I think the generated list should override iterator(), and return an Iterator
> that calculates the list size once per iteration.
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