Hi Raymond, thank you for your response. It's a few things. First, yes, the finalizer is not called in the case of the leak. Second, I am using YourKit profiler and in the case of the leak I can see many Derby classes still loaded along with the classloader that loaded them. Also, I have been using jmap and jhat to dump the heap and look at the loaded classes and in the cases that I am calling "leak" the Derby classes are still loaded. Finally, the reason for all my work on this, if I run this test code in a loop instead of a single run it eventually causes an OOM PermGen space, which is the same error our app experiences after a few restarts. By simply not running the two SQL statements the test can run indefinitely without an OOM.
Thanks, Jason On Mon, Apr 12, 2010 at 3:40 PM, Raymond Kroeker <raykroe...@gmail.com>wrote: > Can you describe the symptom of a leak? Is it that the finalizer > isn't called or is there some other criteria by which the judgement is > being made? > > Raymond > > On Mon, Apr 12, 2010 at 13:29, Jason von Nieda <ja...@vonnieda.org> wrote: > > Hi all, > > I have been tasked with finding a classloader leak in our application and > I > > have been slowly tracking it down to the Derby embedded driver. To test > this > > I wrote a small test case outside of our application that simply loads > Derby > > into a second classloader and causes it to create a drop a table. These > > actions, even after the proper Derby shutdown procedures cause the > > classloader to not be unloadable. Can someone take a look at the code > below > > and tell me if I am missing something, or is this perhaps a known issue? > > I've done quite a bit of searching and the main thing I found > > was https://issues.apache.org/jira/browse/DERBY-3745 which seems to have > > been fixed. > > I am using Derby 10.5.3.0. > > Interestingly, I have found that loading the driver and opening a > connection > > doesn't cause the leak but any execution of a statement does. > > The code I am using to test this is at http://pastebin.com/pJBdGBVT . > Main > > is the test case itself, Test is the class which is used to load Main > into a > > child classloader and TestClassloader is just an extension of > URLClassLoader > > that lets me see when it has been finalized. > > Of note is that if I don't execute the two statements the case does not > > leak. I have also tested this with hsqldb and after adding the Logging > > shutdown at the end of stop() it also does not leak. > > Thanks, > > Jason > > > > > > -- > --------------------------------------------------------- > Raymond Kroeker >
