Hi Jochen, what you can try is to use this code written by Jerome Pilliet as replacement of ClassValue (using -Xbootclasspath/p) https://bitbucket.org/jpilliet/libcore-292/src/tip/libdvm/src/main/java/java/lang/ClassValue.java?at=4.4.3.292 to see if you can reproduce your bug or not with this other implementation of ClassValue (under Apache Licence).
Note that i hope that this implementation works but it's clearly haven't been battletested, nevertheless if you can not reproduce your issue, it means that this is clearly a bug in the OpenJDK implementation. regards, Rémi ----- Mail original ----- De: "Jochen Theodorou" <blackd...@gmx.org> À: "Da Vinci Machine Project" <mlvm-dev@openjdk.java.net> Envoyé: Mercredi 26 Août 2015 22:40:53 Objet: Re: ClassValue rooting objects after it goes away? Am 07.08.2015 13:04, schrieb Michael Haupt: > Hi Charles, > > the pull request mentions a class named Java7ClassValue - does this mean > it's a Java 7 issue or is it reproducible on 8 and maybe even 9? Names > can be misleading. ;-) > > To clarify: by what means is the ClassValue removed in the JRuby > implementation? > > I agree this should not happen. coming back on this and after spending the whole day on debugging a permgen issue (and Cedric actually 3 days) that seems to be related to this. I am not from the Ruby guess, so I will show the Groovy part. We discovered a permgen issue, that prevents the groovy runtime from unloading and the reason turned out to be ClassValue. We get a similar graphic Charles got, only a bit more complex. In my test scenario we load the Groovy runtime in an URLClassLoader, call a method to cause the runtime to initialize and then forget about it, just to do this again in a loop. What happens is that we get into a permgen problem, since the loader cannot be unloaded because ClassValue seems to keep classes from that loader to unload. I tested this with 7_60, 7_65, 8_25, and jdk1.9.0-ea-b68. All have this problem. As a special bonus we have a lot of system classes with added class values... for example all the primitive types. I suspected ClassValue earlier already and made myself a simple test but it seems the simple version is not going to show me what I want. So it is not as simple as having a classloader load a custom ClassValue class and have the classloader not unloading. Guess we will try the WeakReference vesion next as well... not that is a solution for us. bye blackdrag -- Jochen "blackdrag" Theodorou blog: http://blackdragsview.blogspot.com/ _______________________________________________ mlvm-dev mailing list mlvm-dev@openjdk.java.net http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev _______________________________________________ mlvm-dev mailing list mlvm-dev@openjdk.java.net http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev
