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From EC (Stef van Dijk): We have someone here who is moving a large number of projects from VAME to Eclipse. We're talking about over 150 projects which are loaded into the workspace at one time. Note that this is actually a normal configuration for the type of work this person does. Having moved these projects, we are now seeing a performance issue we don't quite understand. Every time a file is changed, a progress dialog appears with an updating message which says "Reading resource change information" followed by the names of all the projects in the workspace. This dialog lasts about 20-30 seconds. Now if we were changing java source and there were numerous interrelated projects I could understand, but that does not appear to be the case. For example, we created a brand new java project which has no references to any of the other 150+ projects (nor do the other projects reference this new one). We then created an .xml file in this project and opened it in an editor. Everytime we save the .xml file, we see the progress dialog racing through all the other projects in the workspace. Why is this? None of those projects should be affected by this project, and certainly not by a change to an .xml file. Then Philippe said: The "Reading resource change information" message indicates the Java builder is asking the platform for the delta computations. When the build button is pressed, all Java projects are traversed to see if they need to be rebuild based on the changes in them and the changes in their prerequisites. Note that a change inside a resource file on the classpath still need the Java builder to copy it into the binary output location. NOTES: JohnA (10/5/2001 5:20:45 PM) A massive improvement here could be accomplished as follows: - find out the set of projects that have changed - for each builder, if any of its "interesting projects" have changed, invoke builder This would mean we don't even have to invoke the builder if we know it won't be interested in any changes.
Fixed. Summary of changes (all in BuildManager and ResourceDeltaFactory: - not eagerly opening the tree for builds (means less tree layers) - Before invoking a builder, compute dtree delta since last build and see if there are any changes to project this builder cares about. If not, the builder is not invoked - When builder requests a delta, see if that project has changed (by looking at dtree delta computed above), and return an empty delta if not changed (saves building a ResourceDelta naively). - Cache the last ResourceDelta requested by a builder. If the old and new trees haven't changed since last request, just return the cached copy. The cache expires at the end of any build cycle to avoid holding onto large garbage structures.
PRODUCT VERSION: R0.9
Fixed in v205.
