DevMode uses single top level ModuleDef with single set of jars.
GWT Designer can open several editors with several top level ModuleDefs, which use several may be different sets of jars, but with many intersections. If only we could have hashCode() and equals() for PathPrefixSet... This would allow not only cashing and reusing indexed jars, but also results of resource requests - another 15% of performance... http://gwt-code-reviews.appspot.com/1388803/diff/1/dev/core/src/com/google/gwt/dev/resource/impl/ZipFileClassPathEntry.java File dev/core/src/com/google/gwt/dev/resource/impl/ZipFileClassPathEntry.java (right): http://gwt-code-reviews.appspot.com/1388803/diff/1/dev/core/src/com/google/gwt/dev/resource/impl/ZipFileClassPathEntry.java#newcode85 dev/core/src/com/google/gwt/dev/resource/impl/ZipFileClassPathEntry.java:85: private static final Map<String, ZipFileCachedEntry> entryCache = new ReferenceMap( WeakHashMap is for weak reference on key. SoftReference is for memory-sensitive cache. http://gwt-code-reviews.appspot.com/1388803/diff/1/dev/core/src/com/google/gwt/dev/resource/impl/ZipFileClassPathEntry.java#newcode98 dev/core/src/com/google/gwt/dev/resource/impl/ZipFileClassPathEntry.java:98: entryCache.put(location, cachedEntry); In reality memory consumption is lower with caching. We don't generate new ZipFileClassPathEntry with all its ZipResources. With cache: 14 instances, 8.5MB Without cache: 30 instances, 29MB Cache prevents creating several instances for same jar. Keep in mind difference of DevMove and DesignMode. First uses fixed set of jars in classpath. Second uses several set of jars, possibly different in different editors, but often there are same jars. Most prominent of these "same jars" in JRE jars (which may be should not be indexed at all) and gwt-user.jar if all GWT modules of user use same version of GWT. Check isStale() is mostly paranoidal - what if user closed all its GWT Designer editors and replaced some jar with newer version, but using same name. This almost never happens, but it is easy and cheap to implement such check. It is not possible to have several versions of same jar - if they have same URI, then old one was replaced with newer. You are right about synchronization. It is required for entryCache and also for findApplicableResources(). http://gwt-code-reviews.appspot.com/1388803/ -- http://groups.google.com/group/Google-Web-Toolkit-Contributors
