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https://issues.apache.org/jira/browse/ADFFACES-394?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Matthias Weßendorf updated ADFFACES-394:
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Affects Version/s: (was: 2.0.0-incubating-core-SNAPSHOT)
(was: 1.0.0-incubating-core)
1.0.1-incubating-core-SNAPSHOT
> Style sheet processing optimization
> -----------------------------------
>
> Key: ADFFACES-394
> URL: https://issues.apache.org/jira/browse/ADFFACES-394
> Project: MyFaces ADF-Faces
> Issue Type: Improvement
> Components: Skinning
> Affects Versions: 1.0.1-incubating-core-SNAPSHOT
> Environment: Windows XP
> Reporter: Andy Schwartz
> Priority: Minor
>
> While investigating performance of initial page delivery I noticed that on
> the very first page delivery a large percentage of the time is spent in style
> sheet processing code. In particular, a bit of profiling reveals that
> StyleSheetDocument.getStyles() - specifically the calls to _resolveStyle() -
> can be expensive. On a slower machine with a large custom stylesheet this
> can add up to several seconds. Interestingly, this particular performance
> problem is self-documenting... The following comment taken from
> StyleSheetDocument.java:
> // Now, loop through all StyleNodes in all StyleSheetNodes
> // Note: The algorithm used here is actually much more inefficient
> // than it needs to be. We're using a n-squared algorithm here -
> // for every style we find, we need to loop through all other styles.
> // The reason for this is because this allows us to share code
> // (namely _resolveStyle()) with getStyleBySelector/Name(). However,
> // we could probably double the performance of CSS generation by
> // optimizing this routine to make a single pass through all styles,
> // and then resolve everything in one step.
> Leaving aside questions about whether "doubling" the performance would be the
> actual result :-) , the idea is that this would work as follows:
> - First pass built up a mappings from selector/name to a list of matching
> StyleNodes.
> - The second pass then resolves the styles based on the mappings created in
> the first pass.
> This should avoid the current n-squared behavior and presumably reduce the
> amount of time spent in this code, thus speeding up initial page delivery.
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