Adrian <[EMAIL PROTECTED]> wrote on 25/05/2007 12:44:54: > On Thu, 2007-05-24 at 11:00 +0100, Glyn Normington wrote: > > A better approach would be for the Java 7 platform to provide first > > class support for JSR 291. This boils down to standardising the > > experimental class loader deadlock fix ([1]) > > Fixing the deadlock just moves the problem. > > You'll still get ClassCircularityErrors when competing threads > try to load classes using locks other than the classloader > synchronization or they don't synchronize on the loadClass() > or they release the lock during the classloading request > to let others have a go (again to avoid the deadlock). > > This is because of the way the dictionary class determines > whether a circular load is occuring. > > Although I haven't tried it with OpenJDK so maybe the > dictionary class contains some other fixes to workaround the > problem? > > The simple form of the problem: > http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4699981 > has been fixed in recent JDKs, but spurious CCEs > still exist in other cases. > e.g. the testAbstractFactoryConcurrent() here: > http://viewvc.jboss.org/cgi-bin/viewvc. > cgi/jbossas/projects/microcontainer/trunk/classloader/src/tests/org/jboss/test/classloader/delegate/test/DelegateUnitTestCase. > java?revision=62792&view=markup > will show CCEs in the log if you enable TRACE logging. > > 1445 TRACE [ClassLoaderManager] Run failed with exception > java.lang.ClassCircularityError: > org/jboss/test/classloader/delegate/support/b/TestFactoryImplementation > at java.lang.ClassLoader.defineClass1(Native Method) > at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
Some spurious CCEs were indeed fixed before the experimental deadlock fix was introduced, but there may be more to do to make this fix robust and complete. If you raise a sunbug for the above testcase, best to report it here so that class loader rearchitecture folks can take it into consideration for Java 7. Glyn Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
