Groovy-Eclipse, compile and run are using different classloaders?

In an Eclipse Groovy project, the order of compilation is causing Groovy classloader conflicts.

I just manually deleted the compiled Groovy classes, then ran the app. Works. Now I rerun still works. Now add a simple blank line to one of the sources and run. It died. Manually delete the output class files, works again. 🙁

Strange I don’t have “rebuild automatically” turned on. Also strange, in the project properties, for builders, only the Java builder is listed.

The console output when I get the error:

Caught: groovy.lang.MissingMethodException: No signature of method: static main.SimpleServerSupport.keepAlive() is applicable for argument types: (main.QuestionServer, java.lang.Long) values: [main.QuestionServer@b32ed4, 60000] Possible solutions: keepAlive(main.QuestionServer, java.lang.Long)

The following classes appear as argument class and as parameter class, but are defined by different class loader:
main.QuestionServer (defined by ‘groovy.lang.GroovyClassLoader$InnerLoader@16921fd’ and ‘’)

If one of the method suggestions matches the method you wanted to call,
then check your class loader setup.
at main.QuestionServer.main(QuestionServer.groovy:72)

Haven’t solved this yet. I can’t find any reference to something like it. Maybe I just have a config issue?

I now remember that the plugin adds hooks into the Java compiler. So is the compiler used different when you run the app with “run as Groovy script” then when Java builder executes, that is what the Classloader names would suggest? But, that makes no sense, since at run time, the classloader hierarchy has nothing to do with the compile, or does it, since Groovy precompiles at runtime?

Yes, I uninstalled the Groovy feature and reinstalled.
Running the same program (script) at the command line is fine.

Todo: Post some code that exhibits the issue. The current code is still at the “throw at wall and see what sticks” stage.


  • 20110328T2010-5: Solved it. I moved a method from a support class, into the main SimpleServer class. This method was using an Executor.newScheduledThreadPool(1) to start a thread to limit the server’s lifetime, it also did a little console spinner to show that there is something running. I don’t see how that is related to classloaders.

Windows 7 64bit Professional
Eclipse Helios Service Release 2
Groovy-Eclipse Feature 2.1.3.xx-20110317-1200-e36

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