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http://issues.apache.org/bugzilla/show_bug.cgi?id=31903 WebappClassLoader fails to load class form local repository ------- Additional Comments From [EMAIL PROTECTED] 2004-10-27 14:26 ------- This is a reproducible real problem. Our server uses tomcat 5.0 as a servlet engine. When it runs multiple worker threads to execute a JavaScritpt (using Rhino) on the server side, it will occasionally but consistently throw NoClassDefFoundError on a class in Rhino library, which is located in the WEB-INF\lib directory. We eventually figure out if two threads start to load same class concurrently for WEB-INF/lib, one of them will fail if a) the first thread manages to call defineClass on the resource entry and set the binaryContent to null; b) when the second adds its entry to the HashMap, it will find an entry for that class already exists, so it will return the existing entry (the one whose binaryContent is null); For the second part, it has been reported by some other people. Please see the following link http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html It would be better to replace the code with single checked locking and make it thread-safe. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
