Mapping ResourceReferences to Urls is slow
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Key: WICKET-3511
URL: https://issues.apache.org/jira/browse/WICKET-3511
Project: Wicket
Issue Type: Bug
Components: wicket-core
Reporter: Matt Brictson
Attachments: CachingResourceStreamLocator.java
PackageResourceReference is often used for stylesheets and JavaScript
resources, many of which can appear on a typical page (WicketAjaxReference is
one common example). Every time the page is rendered, these resources are
mapped to urls in order to build the appropriate <link href="..."> or <script
src="..."> tags.
The trouble is that this mapping process is extremely inefficient. To map a
ResourceReference to a url, ResourceReference#getLastModified() must be
consulted for FilenameWithTimestampResourceCachingStrategy, and
ResourceReference#getUrlAttributes() is called to append appropriate query
parameters.
In PackageResourceReference, both of these methods delegate to the very
expensive PackageResourceReference#lookupStream(), which makes several attempts
to locate the underlying file or classpath item using various permutations of
locale, style, and variation. Each of these attempts involves I/O. The default
ResourceStreamLocator, which does the actual file and classpath queries, does
no caching whatsoever.
On a trivial Wicket page containing 7 total PackageResourceReferences for
images, stylesheets and JavaScript files, the average response time in my tests
was 300 ms. The vast majority of that time was spent in ResourceStreamLocator,
due to the expensive steps described above.
It seems that putting caching at the ResourceStreamLocator would be extremely
beneficial. I am attaching a simple implementation. With caching enabled in
ResourceStreamLocator, the response time of my test page dropped from 300 ms to
30 ms.
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