Hey Re: -Djava.system.class.loader=org.aspectj.weaver.loadtime.Weavi ngURLClassLoader
Been a while since I've tried that, I half expected that property not to work, but (on Java8) if I set it and I set aj.aspect.path then I see WeavingURLClassLoader kick in and try to work - it gets stuck in a recursive invocation problem though. Not sure what that is. Caused by: java.lang.IllegalStateException: recursive invocation at java.lang.ClassLoader.initSystemClassLoader(ClassLoader.java:1443) at java.lang.ClassLoader.getSystemClassLoader(ClassLoader.java:1429) at java.util.ServiceLoader.loadInstalled(ServiceLoader.java:568) at java.util.ResourceBundle.<clinit>(ResourceBundle.java:376) at org.aspectj.weaver.WeaverMessages.<clinit>(WeaverMessages.java:19) at org.aspectj.weaver.bcel.ClassPathManager.addPath(ClassPathManager.java:103) Re: weaving java/javax I think we've often said if you need to do that, do it offline and used a patched rt.jar/equivalent as it is more reliable. I can fully believe the JDK has moved on in terms of class loading mechanisms and AspectJ hasn't kept up. cheers, Andy On Mon, 6 Apr 2020 at 05:15, Alexander Kriegisch <alexan...@kriegisch.name> wrote: > One more question: What exactly is it good for to be able to replace the > system classloader by WeavingURLClassLoader via: > > > -Djava.system.class.loader=org.aspectj.weaver.loadtime.WeavingURLClassLoader > > For me this does not do anything without an additional weaving agent > attached via '-javaagent:...'. Can you explain, maybe? > > Source code reference: > > https://github.com/eclipse/org.aspectj/blob/8c6b3ae13b105ce9bb9559de0ee4752cab5ba81c/loadtime/src/org/aspectj/weaver/loadtime/WeavingURLClassLoader.java#L48 > > -- > Alexander Kriegisch > https://scrum-master.de > > > Alexander Kriegisch: > > > I tried '-verbose:class' both with normal LTW configuration and with > > the weaving agent additionally prepended to the boot classpath via > > '-Xbootclasspath/p:/my/path/aspectjweaver.jar"'. Except for the weaver > > classes being loaded earlier in the latter case, the result is the > > same: > > > > Only classes from AppClassLoader yield any AspectJ log message, woven > > or not. JRE classes are being ignored, I see no other classloader > > being attached. Actually there does not seem to be any specific debug > > logging for names of attached classloaders at all, I only indirectly > > see things like "[AppClassLoader@18b4aac2] debug not weaving > > 'a.b..C'". > > > > > > Andy Clement: > > > >>> Furthermore, both '-verbose:class' and '-verbose=class' yield > >>> warnings > >> > >> That's not a weaver option, it is a JVM option for showing class > >> loading. I thought pairing that with the -debug weaver option might > >> show java types being loaded by the JVM and if there was no immediate > >> weaver message then they weren't getting to the weaver. > >> > >> It is interesting what classloaders weavers get attached to. I can't > >> what the current class loader hierarchy is in Java8 - do you only see > >> the one weaver attached to application related class loader? > >> > >> > >> Alexander Kriegisch: > >> > >>> Actually, I am still running Java 8, so modules are not an issue > >>> here. > >>> > >>> Furthermore, both '-verbose:class' and '-verbose=class' yield > >>> warnings: > >>> > >>> [MethodUtil@1e51f2fa] warning Cannot configure weaver with option > >>> '-verbose:class': unknown option > >>> > >>> I run with these settings: > >>> > >>> <weaver options="-showWeaveInfo -verbose -debug > >>> -Xset:weaveJavaxPackages=true,weaveJavaPackages=true"> > >>> <include within="javax..*"/> > >>> <include within="java..*"/> > >>> <include within="org.aspectj..*"/> > >>> </weaver> > >>> > >>> I see nothing on the console indicating that any JRE classes are > >>> even visible to the classloader. I even created a main class > >>> starting my other main class via Class.forName(), Class.getMethod() > >>> and Method.invoke() in order to avoid javax or java JRE imports in > >>> my main class, trying to avoid that the weaver kicks in too late. It > >>> seems as if the weaver does not get attached to the right > >>> classloader. Should I do more than just '-javaagent:...' and also > >>> add the weaver to the boot classpath or something? > >>> > >>> I found a test related to javax classes, but that one is kinda > >>> cheating because it tests with own classes in javax package not with > >>> real JRE classes: > >>> > >>> > https://github.com/eclipse/org.aspectj/tree/master/tests/features160/weavingJavaxPackage > >>> > >>> I really need some help to get started here. > >>> > >>> > >>> Andy Clement: > >>> > >>>> I feel like they used to work but there were gotchas. For example > >>>> the JVM loads up some types before the LTW infrastructure can even > >>>> get involved and those can't be woven. I don't actually recall if > >>>> we have testcases for this but I wouldn't be surprised if they > >>>> weren't there. I guess you have tried them and they don't work - I > >>>> wonder if you were test weaving something that would be loaded > >>>> early? It would be interesting to attempt it with a -verbose:class > >>>> and verify not attempting to weave things loaded before the 'LTW is > >>>> active' type messages come out. Will it work with modules in recent > >>>> Javas? That seems unlikely. > >>>> > >>>> But it could be the kind of classloaders in use in regular Java now > >>>> don't allow weaver attachment, I honestly haven't kept up to speed > >>>> on that - and maybe that prevents them working at all. A run of LTW > >>>> with the debug option on for the weaver should show the types the > >>>> weaver is being exposed to. If those are java/javax then they > >>>> should be weavable. > >>>> > >>>> > >>>> Alexander Kriegisch: > >>>> > >>>>> The AspectJ documentation still mentions things like > >>>>> > >>>>> -Xset:weaveJavaxPackages=true > >>>>> -Xset:weaveJavaPackages=true > >>>>> > >>>>> or for LTW > >>>>> > >>>>> <include within="javax.*"/> > >>>>> <include within="java.*"/> > >>>>> <include within="org.aspectj.*"/> > >>>>> > >>>>> (I think "java..*" would be correct syntax, BTW.) > >>>>> > >>>>> None of these work. Yes, there are valid cases in which users > >>>>> might want to use LTW on JRE classes. The only way I could ever > >>>>> weave into the JRE (execution joinpoints, not just call from my > >>>>> own woven code) was binary weaving and creating my own (subset of) > >>>>> JRE, prepending it to the boot classpath. But that's not nice and > >>>>> I never tried with modularised Java 9+, which might work or not. > >>>>> > >>>>> Before I create a Bugzilla ticket I would like to get a maintainer > >>>>> opinion. Is there any chance to make this work with AspectJ LTW? > >>>>> Is is maybe possible already and I just do it wrong? > _______________________________________________ > aspectj-users mailing list > aspectj-users@eclipse.org > To unsubscribe from this list, visit > https://www.eclipse.org/mailman/listinfo/aspectj-users >
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