VM Spec 8.14 Suppose that thread T has in fact performed N lock operations that have not been matched by unlock operations. The wait method then adds the current thread to the wait set for the object, disables the current thread for thread scheduling purposes, and performs N unlock operations to relinquish the lock.
Regards, Adrian > |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 > | > |-----Urspr�ngliche 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.loadClassLoc > lly(UnifiedCla > |ssLoader.java:180) > || at > ||org.jboss.mx.loading.UnifiedLoaderRepository.loadCla > s(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(Un > fiedClassLoade > ||r.java:217) > || at > java.lang.ClassLoader.loadClass(ClassLoader.java:255) > || at > java.lang.ClassLoader.loadClassInternal(ClassLoader.ja > a:315) > || - locked <43eefa48> (a > org.jboss.mx.loading.UnifiedClassLoader) > || at > ||com.entrust.toolkit.PKCS7EncodeStream.e(PKCS7EncodeS > ream.java) > || at > ||com.entrust.toolkit.PKCS7EncodeStream.f(PKCS7EncodeS > ream.java) > || at > ||com.entrust.toolkit.PKCS7EncodeStream.write(PKCS7Enc > deStream.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.loadClassLoc > lly(UnifiedCla > |ssLoader.java:180) > || at > ||org.jboss.mx.loading.UnifiedLoaderRepository.loadCla > s(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(Un > fiedClassLoade > ||r.java:217) > | > || at > java.lang.ClassLoader.loadClass(ClassLoader.java:255) > || at > java.lang.ClassLoader.loadClassInternal(ClassLoader.ja > a: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(LoginC > ntext.java:626) > || at > ||javax.security.auth.login.LoginContext.access$000(Lo > inContext.java:129) > || at > ||javax.security.auth.login.LoginContext$4.run(LoginCo > text.java:599) > || at > java.security.AccessController.doPrivileged(Native > Method) > || at > ||javax.security.auth.login.LoginContext.invokeModule( > oginContext.java:596) > || at > ||javax.security.auth.login.LoginContext.login(LoginCo > text.java:523) > || at > com.candata.util.beans.CandataClientLogin.login(Unknow > > ||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-de > elopment > | > |_______________________________________________ > |Jboss-development mailing list > |[EMAIL PROTECTED] > |https://lists.sourceforge.net/lists/listinfo/jboss-de > elopment > > > _______________________________________________ > Jboss-development mailing list > [EMAIL PROTECTED] > https://lists.sourceforge.net/lists/listinfo/jboss-dev > lopment * * * View thread online: http://jboss.org/forums/thread.jsp?forum=66&thread=13760 _______________________________________________ Jboss-development mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-development
