https://issues.apache.org/bugzilla/show_bug.cgi?id=43867
--- Comment #58 from Aaron Digulla <[EMAIL PROTECTED]> 2008-08-06 12:24:29 PST --- Re: Field.get(Object) Some background info on reflection and static code in a class. If you use reflection to access the static data of a class (which Tomcat has to do to clear static references so it can GC the webapp), then calling Field.get() will initialize a class if a) it hasn't been initialized, yet, b) if it has been initialized by a different classloader instead of the current one or c) when the class itself has been GC'd (not with Sun VM with default GC options but you can activate that). There are a lot of spurious problems lurking around this "feature"; I once used it to execute code while the Groovy compiler worked on my class file. It wasn't nice. So what can happen is that you need a class for something (i.e. someone imports it) but you don't actually use it. In this case, the classloader will have loaded the class but it won't be initialized. That's a standard optimization to make Java boot faster. Then, you shutdown. At that stage, Tomcat will look through all loaded classes (instead of those which are initialized) and call Field.get(). And that triggers the bug. Tomcat can't solve this, because there is no way to ask the VM if a class is initialized or not. The only solution for this kind of bug is not to use *any* static fields in code which will be deployed to Tomcat. Especially the Loggers of log4j must not be static ... and here we run into trouble because we have to mutually exclusive design goals. But maybe we can hack our way out of this. Solution 1 would be to install a listener which deinitializes log4j in such a way that any getLogger() call would return null or a NOPLogger or something. Solution 2 would be to create a private final static field which Tomcat will eventually clear. If that field is cleared (and only Tomcat can do that since it's private), you know that you're in the Tomcat shutdown cycle (instead of some misconfiguration error) and you could ignore attempts to log anything instead of throwing an error. Solution 1 would depend a bit on Tomcat but it would be reusable for other app servers. Solution 2 would be independent of the appserver; any appserver who clears static fields would just work. -- Configure bugmail: https://issues.apache.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
