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From "Jed Wesley-Smith (JIRA)" <j...@apache.org>
Subject [jira] Created: (WW-3457) Significant performance improvement for freemarker TagModel
Date Thu, 10 Jun 2010 05:25:15 GMT
Significant performance improvement for freemarker TagModel
-----------------------------------------------------------

                 Key: WW-3457
                 URL: https://issues.apache.org/jira/browse/WW-3457
             Project: Struts 2
          Issue Type: Improvement
    Affects Versions: 2.0.0
            Reporter: Jed Wesley-Smith


The class org.apache.struts2.views.freemarker.tags.TagModel creates a new freemarker.template.DefaultObjectWrapper
for each call to unwrapParameters(Map). The problem is that that class is quite expensive
to construct as the super-class does a quite bit of introspection to fill up its caches. Not
only is this a lot of work, it tends to hit the Introspector class pretty hard, which internally
does a lot of sychronising. In our soak performance tests this was a significant cause of
blocking in our application.

The DefaultObjectWrapper (or more properly the freemarker.ext.beans.BeansWrapper class as
that is actually all the TagModel is using) is actually meant to be a cache that prevents
exactly this kind of slowness, so constructing a new one every time is counter-productive.

I don't have the latest source handy so I can't provide a patch, but the change is to simply
replace the line:

    	DefaultObjectWrapper objectWrapper = new DefaultObjectWrapper();

with:

        BeansWrapper objectWrapper = BeansWrapper.getDefaultInstance();

in the second line of TagModel.unwrapParameters(Map params)

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