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List:       xmlbeans-dev
Subject:    [jira] Created: (XMLBEANS-389) List accessors generated with
From:       "Philip Aston (JIRA)" <xmlbeans-dev () xml ! apache ! org>
Date:       2008-11-13 13:21:44
Message-ID: 814560199.1226582504267.JavaMail.jira () brutus
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List accessors generated with -javasource=1.5 produce lists that scale poorly with \
                the size of the list
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                 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


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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