Help: weblogic.ejb.extensions.LockTimedOutException

Question

Dear All:
          I got this exception in our EJB app:
          weblogic.ejb.extensions.LockTimedOutException. Please see attached error
          message below. It is not happening every time you call the bean. It is
          reproducable with patience.
          Have you had this kind of problem and more importantly, how to avoid it?
          Our env is: Wl51 with sp 10, jdk1.3.02, Sun Solaris Unix, a cluster contains
          2 wl instance
          Thanks.
          Wed Jun 19 14:26:53 EDT 2002:<I> <TX> Transaction (TxC (5488304, xid =
          1024502557372_6636, timeout = 300, txState = Marked Rollback, root = null)
          rolled back after 300 sec.
          [GC 99080K->85533K(130688K), 0.0227977 secs]
          Wed Jun 19 14:26:54 EDT 2002:<I> <EJB JAR deployment
          /webapp/dtshc/dts/nmc/ejb/nmcejb.jar> Transaction: '1024502557372_6636'
          rolled back due to EJB exception:
          weblogic.ejb.extensions.LockTimedOutException: Lock for
          primaryKey:com.mm.nmc.entity.ProducerOneYearPlanPK@1700fc timed out after
          300000 ms.
          at
          weblogic.ejb.internal.LockManagerImpl.waitForLock(LockManagerImpl.java:53)
          at weblogic.ejb.internal.LockManagerImpl.lock(LockManagerImpl.java:146)
          at weblogic.ejb.internal.LockManagerImpl.lock(LockManagerImpl.java:81)
          at weblogic.ejb.internal.StatefulEJBCache.bind(StatefulEJBCache.java:456)
          at
          weblogic.ejb.internal.StatefulEJBObject.getContextForInvoke(StatefulEJBObjec
          t.java:162)
          at weblogic.ejb.internal.BaseEJBObject.preInvoke(BaseEJBObject.java:476)
          at
          com.mm.nmc.entity.ProducerOneYearPlanEJBEOImpl.getData(ProducerOneYearPlanEJ
          BEOImpl.java:979)
          at
          com.mm.nmc.session.PersonalTacticalSessionEJB.getTacticalPlanGoals(PersonalT
          acticalSessionEJB.java:200)
          at
          com.mm.nmc.session.PersonalTacticalSessionEJB.getPersonalTacticalPlan(Person
          alTacticalSessionEJB.java:165)
          at
          com.mm.nmc.session.PersonalTacticalSessionEJB.getPersonalTacticalPlan(Person
          alTacticalSessionEJB.java:155)
          at
          com.mm.nmc.session.PersonalTacticalSessionEJBEOImpl.getPersonalTacticalPlan(
          PersonalTacticalSessionEJBEOImpl.java:340)
          at
          com.mm.nmc.session.PersonalTacticalSessionEJBEOImpl_WLSkel.invoke(PersonalTa
          cticalSessionEJBEOImpl_WLSkel.java:167)
          at
          weblogic.rmi.extensions.BasicServerObjectAdapter.invoke(BasicServerObjectAda
          pter.java:347)
          at
          weblogic.rmi.extensions.BasicRequestHandler.handleRequest(BasicRequestHandle
          r.java:86)
          at
          weblogic.rmi.internal.BasicExecuteRequest.execute(BasicExecuteRequest.java:1
          5)
          at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:129)
          Jiancai He
          http://www.hefamily.com
          

Answer 1

Thanks for your message:
          In our case, it is entity EJB. The problem only happens in clustered env,
          and only happens in one of the servers.
          Question: can wl51 use database to manage the concurrent access of entity
          EJBs?
          Thanks.
          Jiancai
          Jiancai He
          http://www.hefamily.com
          "ludovic le goff" <[email protected]> wrote in message
          news:[email protected]...
          > Hello,
          >
          > Basically, it means two (or more) different threads are trying to get an
          > exclusive lock on the same entity bean or stateful session bean at the
          same
          > time. One of the locks eventually times out and this exception is thrown.
          >
          > There are several things that could cause this, for instance:
          >
          > - Two threads trying to invoke a method on the same stateful session bean
          at
          > the same time. The EJB 1.1 spec states that the server must detect this
          > condition and throw a RemoteException to all subsequent callers.
          > LockTimedOutException is a sub-class of java.rmi.RemoteException.
          >
          > - Two threads are trying to access the same entity bean instance inside a
          > single server in the cluster, and the caller holding the lock does not
          > finish fast enough.
          >
          > You might want to check if you have declared the Remote and home interface
          > in your jsp/servlet as global variable. And since it's global, instance
          > getting overridden every time. That's why both the two request end up in
          > using the same EJBObject.
          >
          > You should changed your code and make the remote/home interface variable
          > declaration as local i.e. within the scope of a single request.
          > Then you should not see any problem. Both the threads will use different
          > EJBObjects and hence you should not see any exceptions.
          >
          > You need to code in such a way as to avoid deadlocks. For instance, if
          > more than one client accesses the EJBs in different order, a deadlock may
          > occur. This deadlock is detected and after a certain timeout (5 minutes by
          > default), the deadlock is removed and one of the clients gets a
          > LockTimedOutException. For example, if one request in your application has
          > entity Account 1 (by doing an ejbFindByPrimaryKey) and is then about to
          get
          > Customer 1, and if at the same time another request in another business
          > method has got Customer 1 and is waiting for Account 1, you'll get a
          > deadlock and a LockTimedOutException after 5 minutes. You could avoid
          this
          > by include the code in a synchronized block. You could also get a
          deadlock
          > if you're making a reentrant call, e.g., A calls B which calls back to A.
          >
          > If you haven't already seen this, here's a blurb from "Locking Model for
          > Entity EJBs" at
          >
          http://www.weblogic.com/docs51/classdocs/API_ejb/EJB_environment.html#108796
          > 7 that you might find interesting:
          >
          > The EJB 1.1 container in WebLogic Server Version 5.1 uses a pessimistic
          > locking mechanism for entity EJB instances. As clients enlist an EJB or
          EJB
          > method in a transaction, WebLogic Server places an exclusive lock on the
          EJB
          > instance or method for the duration of the transaction. Other clients
          > requesting the same EJB or method block until the current transaction
          > completes.
          >
          > This method of locking provides reliable access to EJB data, and avoids
          > unnecessary calls to ejbLoad() to refresh the EJB instance's persistent
          > fields. However, in certain circumstances pessimistic locking may not
          > provide the best model for concurrent access to the EJB's data. Once a
          > client has locked an EJB instance, other clients are blocked from the
          EJB's
          > data even if they intend only to read the persistent fields.
          >
          > In a Nutshell the first exception is a consequence of the second.
          >
          > Hope this helps,
          > Ludovic.
          > Developer Relations Engineer
          > BEA Customer Support
          > "newsgroups.bea.com" <[email protected]> a écrit dans le message news:
          > [email protected]...
          > > Dear All:
          > >
          > > I got this exception in our EJB app:
          > > weblogic.ejb.extensions.LockTimedOutException. Please see attached error
          > > message below. It is not happening every time you call the bean. It is
          > > reproducable with patience.
          > >
          > > Have you had this kind of problem and more importantly, how to avoid it?
          > >
          > > Our env is: Wl51 with sp 10, jdk1.3.02, Sun Solaris Unix, a cluster
          > contains
          > > 2 wl instance
          > >
          > > Thanks.
          > >
          > >
          > >
          > >
          > >
          > >
          > >
          > >
          > >
          > >
          > >
          > > Wed Jun 19 14:26:53 EDT 2002:<I> <TX> Transaction (TxC (5488304, xid =
          > > 1024502557372_6636, timeout = 300, txState = Marked Rollback, root =
          null)
          > > rolled back after 300 sec.
          > >
          > > [GC 99080K->85533K(130688K), 0.0227977 secs]
          > >
          > > Wed Jun 19 14:26:54 EDT 2002:<I> <EJB JAR deployment
          > > /webapp/dtshc/dts/nmc/ejb/nmcejb.jar> Transaction: '1024502557372_6636'
          > > rolled back due to EJB exception:
          > >
          > > weblogic.ejb.extensions.LockTimedOutException: Lock for
          > > primaryKey:com.mm.nmc.entity.ProducerOneYearPlanPK@1700fc timed out
          after
          > > 300000 ms.
          > >
          > > at
          > >
          weblogic.ejb.internal.LockManagerImpl.waitForLock(LockManagerImpl.java:53)
          > >
          > > at weblogic.ejb.internal.LockManagerImpl.lock(LockManagerImpl.java:146)
          > >
          > > at weblogic.ejb.internal.LockManagerImpl.lock(LockManagerImpl.java:81)
          > >
          > > at
          weblogic.ejb.internal.StatefulEJBCache.bind(StatefulEJBCache.java:456)
          > >
          > > at
          > >
          >
          weblogic.ejb.internal.StatefulEJBObject.getContextForInvoke(StatefulEJBObjec
          > > t.java:162)
          > >
          > > at weblogic.ejb.internal.BaseEJBObject.preInvoke(BaseEJBObject.java:476)
          > >
          > > at
          > >
          >
          com.mm.nmc.entity.ProducerOneYearPlanEJBEOImpl.getData(ProducerOneYearPlanEJ
          > > BEOImpl.java:979)
          > >
          > > at
          > >
          >
          com.mm.nmc.session.PersonalTacticalSessionEJB.getTacticalPlanGoals(PersonalT
          > > acticalSessionEJB.java:200)
          > >
          > > at
          > >
          >
          com.mm.nmc.session.PersonalTacticalSessionEJB.getPersonalTacticalPlan(Person
          > > alTacticalSessionEJB.java:165)
          > >
          > > at
          > >
          >
          com.mm.nmc.session.PersonalTacticalSessionEJB.getPersonalTacticalPlan(Person
          > > alTacticalSessionEJB.java:155)
          > >
          > > at
          > >
          >
          com.mm.nmc.session.PersonalTacticalSessionEJBEOImpl.getPersonalTacticalPlan(
          > > PersonalTacticalSessionEJBEOImpl.java:340)
          > >
          > > at
          > >
          >
          com.mm.nmc.session.PersonalTacticalSessionEJBEOImpl_WLSkel.invoke(PersonalTa
          > > cticalSessionEJBEOImpl_WLSkel.java:167)
          > >
          > > at
          > >
          >
          weblogic.rmi.extensions.BasicServerObjectAdapter.invoke(BasicServerObjectAda
          > > pter.java:347)
          > >
          > > at
          > >
          >
          weblogic.rmi.extensions.BasicRequestHandler.handleRequest(BasicRequestHandle
          > > r.java:86)
          > >
          > > at
          > >
          >
          weblogic.rmi.internal.BasicExecuteRequest.execute(BasicExecuteRequest.java:1
          > > 5)
          > >
          > > at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:129)
          > >
          > >
          > >
          > >
          > >
          > >
          > > --
          > > Jiancai He
          > > http://www.hefamily.com
          > >
          > >
          >
          >