|AFAIK, a thread will only release the lock in the closest synchronization |scope.
hence my previous mail does a double synchronization on the *same* lock release both or not. marcf | |If you can make sure that the UCL itself is the last lock before entering |ULR, then it |should IMHO work. Since we are not in control of loadClassInternal, but of |loadClass, there is the chance |that this will do as wished. | |CGJ | |-----Ursprüngliche Nachricht----- |Von: marc fleury [mailto:[EMAIL PROTECTED]] |Gesendet: Dienstag, 23. April 2002 03:07 |An: Dave Smith |Cc: lsanders; Jboss-Development@Lists. Sourceforge. Net |Betreff: RE: [JBoss-dev] Workaround for CL stuff | | |Solution: | |When a thread goes through loadClass, in the ULR we "lock" with a |field that |tracks the thread. | |Another thread comes in, reaches ULR, we sync on the calling CL |(we know it) |we wait, this releases the lock, we keep track of the CL as part of this |"load". The first thread will always find a CL as no CL can be locked for |ever, since the thread that would reach the ULR would wait. First thread |always finishes (with reentrancy so the count must go on and we track the |fact that it is the same thread). When count reaches 0 we get the |set of CL |that were touched by this thread (i.e. the set of CLs that had threads in |it) and we notifyAll on each element of the set, start this again. | |Done (afaict), I will try to apply it to the stack trace below. | ||I brought this thing back to life and passed the URL of the orginal sun ||bug that they rejected. Here is a quick stack trace of the deadlock. ||Note that you should start jboss with the -Xdebug options so it shows ||you what objects that it is trying to lock. See below for my orginal ||post || || ||"CCRAPoll" prio=5 tid=0x8184f58 nid=0x64ec waiting for monitor entry ||[0xbb7fe000..0xbb7ffad8] || at java.lang.ClassLoader.loadClass(ClassLoader.java:288) || - waiting to lock <43a2c508> (a ||org.jboss.mx.loading.UnifiedClassLoader) || at ||org.jboss.mx.loading.UnifiedClassLoader.loadClassLocally(UnifiedCla |ssLoader.java:180) || at ||org.jboss.mx.loading.UnifiedLoaderRepository.loadClass(UnifiedLoade |rRepository.java:178) | |This one would reach ULR and lock the ULR, see below for lock |<43a2c508> NOT |being locked. | || at ||org.jboss.mx.loading.UnifiedClassLoader.loadClass(UnifiedClassLoade ||r.java:217) || at java.lang.ClassLoader.loadClass(ClassLoader.java:255) || at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:315) || - locked <43eefa48> (a org.jboss.mx.loading.UnifiedClassLoader) || at ||com.entrust.toolkit.PKCS7EncodeStream.e(PKCS7EncodeStream.java) || at ||com.entrust.toolkit.PKCS7EncodeStream.f(PKCS7EncodeStream.java) || at ||com.entrust.toolkit.PKCS7EncodeStream.write(PKCS7EncodeStream.java) || at com.candata.gateway.Encryption.Sign(Unknown Source) || - locked <43f0c6a0> (a com.candata.gateway.Encryption) || at com.candata.gateway.Encryption.createMsg(Unknown Source) || at com.candata.gateway.CCRAAbstract.postMsg(Unknown Source) || at com.candata.gateway.CCRAAbstract.recvMsg(Unknown Source) || at com.candata.gateway.CCRAPoll.run(Unknown Source) || at java.lang.Thread.run(Thread.java:484) || || ||"Thread-20" prio=5 tid=0x81821a8 nid=0x64f9 waiting for monitor entry ||[0xbe7fe000..0xbe7ffad8] || at java.lang.ClassLoader.loadClass(ClassLoader.java:288) || - waiting to lock <43eefa48> (a ||org.jboss.mx.loading.UnifiedClassLoader) || at ||org.jboss.mx.loading.UnifiedClassLoader.loadClassLocally(UnifiedCla |ssLoader.java:180) || at ||org.jboss.mx.loading.UnifiedLoaderRepository.loadClass(UnifiedLoade |rRepository.java:178) | |thread 2 reaches here and sees a ULR under usage. It waits on the calling |UCL (which we know it is passed) and THEREFORE UNLOCKS <43a2c508>. | |Done | |marcf | || at ||org.jboss.mx.loading.UnifiedClassLoader.loadClass(UnifiedClassLoade ||r.java:217) | || at java.lang.ClassLoader.loadClass(ClassLoader.java:255) || at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:315) || - locked <43a2c508> (a org.jboss.mx.loading.UnifiedClassLoader) || at java.lang.Class.forName0(Native Method) || at java.lang.Class.forName(Class.java:195) || at ||javax.security.auth.login.LoginContext.invoke(LoginContext.java:626) || at ||javax.security.auth.login.LoginContext.access$000(LoginContext.java:129) || at ||javax.security.auth.login.LoginContext$4.run(LoginContext.java:599) || at java.security.AccessController.doPrivileged(Native Method) || at ||javax.security.auth.login.LoginContext.invokeModule(LoginContext.java:596) || at ||javax.security.auth.login.LoginContext.login(LoginContext.java:523) || at com.candata.util.beans.CandataClientLogin.login(Unknown ||Source) || at com.candata.bbxinterface.BbxJavaInvoker.login(Unknown Source) || at com.candata.bbxinterface.BbxWrapper.run(Unknown Source) || at java.lang.Thread.run(Thread.java:484) | |marcf | | |_______________________________________________ |Jboss-development mailing list [EMAIL PROTECTED] |https://lists.sourceforge.net/lists/listinfo/jboss-development | |_______________________________________________ |Jboss-development mailing list |[EMAIL PROTECTED] |https://lists.sourceforge.net/lists/listinfo/jboss-development _______________________________________________ Jboss-development mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-development
