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we installed eclipse on a network drive. to start eclipse we also have a batch-file which sets the workspace directory to a subdirectory on the users home network drive. the jdk1.4 is also installed on the global network drive and the eclipse batch uses the "-vm" option to use this network jdk. now it is possible to log in on every workstation and work with eclipse. you always have your own workspace directory. another big advantage is that i can backup every persons workspace directory every night. to support external libraries we have a classpath variable named "LIB_HOME" which also points to a network directory in which we have external libraries. so we can version projects and work at home as long as you replicate the LIB_HOME directory from time to time. everythin works, everythin would be fine, but: we have a performance problem. i used a network sniffer and realized that a simple mouseclick in my packagetree lead to a SMB network call to our samba-server to load some external libraries. i set "-vmargs -Xnoclassgc" in our batch file so that the java vm won't gc the classes. i thought that after some working there would be no need to reload the jars again and again. but it is not so. they are loaded very very often. again and again. another interesting point is the "show referenced libraries" menu entry. by toggling this entry you see that a single library is loaded very often. it seems it is loaded for every project it is referenced. and i think every required project is also traversed. perhaps i'm wrong but in my case i have one project "Tomcat401" which references all tomcat 401 libraries (jar's). every other project which is a webapp simply has this project in its dependencies because i need the TC classes at runtime (not at compile time). when i set the "show referenced libraries" to "true", the sniffer shows that every jar is loaded about 3-5 times or more. and the project has 25 JAR's!!!
We need to investigate our story here. I am suspecting that each shared JAR is opened quite a number of times (once per reference). This sounds true for both the builder and the JavaModel. In the case of the JavaModel, it might be possible to improve this given we share elements underneath. On the builder front, I don't see how we could improve this given we have no hook into the build manager, just on project build operations. Maybe we could setup a cache in the JavaModel manager and use a POST_BUILD delta notification to clear this cache ?
Interesting comment in the same area (http://bugs.eclipse.org/bugs/show_bug.cgi? id=10216).
Now caching the existence check result on external jars. This cache is flushed before building, so that the builder can discover that some external jars have been deleted.
Fixed external jar existence check problem. See bug 10216 for other performance problems.
