Re: [JBoss-user] Can two separate client threads make simultaneouscalls?
Beau Cronin wrote: Muntean Horia wrote: Beau Cronin wrote: I have a Swing app which is essentially single-threaded, accessing the server in the usual way through a session facade. I'd like to do some background loading of certain data for performance reasons, but when I try to do this by using a separate thread (and separate session instance), I get various transaction collision problems if these two threads access the server at the same time. I'm obviously missing something here--shouldn't different remote client threads from the same client be able to access JBoss simultaneously in the same way that entirely different clients can? I.e., shouldn't they spawn separate transactions which are scheduled appropriately by JBoss? Any clarification appreciated, Beau Cronin --- This SF.net email is sponsored by: Scholarships for Techies! Can't afford IT training? All 2003 ictp students receive scholarships. Get hands-on training in Microsoft, Cisco, Sun, Linux/UNIX, and more. www.ictp.com/training/sourceforge.asp ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user Try to do the same thing u are doing with 2 threads in the same VM, in 2 different JVMs. And (as I suspect it would be) if u get the same collisions (tx deadlocks?), your problem resides at the server side. The problem does not occur when multiple users (i.e., many different clients, each with its own JVM) are on the system. This leads me to believe it is not a fundamental server-side problem. It only occurs when two threads from the same client make simultaneous calls. Please see my reply to Alex Loubyansky for the relevant stack traces. Thanks, Beau Regards, Horia --- This SF.net email is sponsored by: Scholarships for Techies! Can't afford IT training? All 2003 ictp students receive scholarships. Get hands-on training in Microsoft, Cisco, Sun, Linux/UNIX, and more. www.ictp.com/training/sourceforge.asp ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user --- This SF.net email is sponsored by: Scholarships for Techies! Can't afford IT training? All 2003 ictp students receive scholarships. Get hands-on training in Microsoft, Cisco, Sun, Linux/UNIX, and more. www.ictp.com/training/sourceforge.asp ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user If u are using Pessimistic Lock policy , any call on a CMP entity (even if the method is a get* one) will register the bean instance in the current Tx and so the bean will be locked. I mean, if u have an AccountBean for example and 1 client calls bean1.getName(); bean2.getName(); and another client (same or separate JVM) bean2.getName(); bean1.getName(), u will get a deadlock eventually. There are some solutions over this: 1. Order carefully the calls to your entity beans. 2. In 3.2. (some say this is in 3.0.x also but I never tried it here) there is a method level tag that marks a certain method of an entity as being RO so the bean won't be blocked by the calling TX. 2. Try the Instance Per Transcation container policy.(but here commit option A doesn't make any sense and logical data consistency is not guaranteed) 3. In 3.2. there is a OptimisticLock policy implementation.(AFAIK commit option A doesn't make sense here either. yet.) Regards, horia --- This SF.NET email is sponsored by: SourceForge Enterprise Edition + IBM + LinuxWorld = Something 2 See! http://www.vasoftware.com ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
Re: [JBoss-user] Can two separate client threads make simultaneouscalls?
These deadlocks are most likely on your entity beans (the second one is fishy looking, but I really can't say much without seeing more (all) of the stack trace.). By default, JBoss only keeps one instance per bean identity, so each transaction from your client will block on the entity. Give the full stack trace, that might be helpful. launching from different client app instances will change the timings of things, making the deadlock less likely, but perhaps still possible, depending on your application. Beau Cronin wrote: There are two messages which appear. The first is: 2003-01-22 11:31:08,725 ERROR [org.jboss.ejb.BeanLock] Application deadlock detected: TransactionImpl:XidImpl [FormatId=257, GlobalId=redbull//3324, BranchQual=] has deadlock conditions. Two or more transactions contending for same resources and each have locks eachother need. 2003-01-22 11:31:08,728 ERROR [org.jboss.ejb.plugins.LogInterceptor] TransactionRolledbackLocalException, causedBy: org.jboss.ejb.plugins.lock.ApplicationDeadlockException: Application deadlock detected: Two or more transactions contention.at org.jboss.ejb.plugins.lock.BeanLockSupport.deadlockDetection(BeanLock Support.java:136)at org.jboss.ejb.plugins.lock.QueuedPessimisticEJBLock.waitForTx(QueuedP essimisticEJBLock.java:270)at org.jboss.ejb.plugins.lock.QueuedPessimisticEJBLock.doSchedule(Queued PessimisticEJBLock.java:202)at org.jboss.ejb.plugins.lock.QueuedPessimisticEJBLock.schedule(QueuedPe ssimisticEJBLock.java:150) smime.p7s Description: S/MIME Cryptographic Signature
Re: [JBoss-user] Can two separate client threads make simultaneouscalls?
Beau Cronin wrote: I have a Swing app which is essentially single-threaded, accessing the server in the usual way through a session facade. I'd like to do some background loading of certain data for performance reasons, but when I try to do this by using a separate thread (and separate session instance), I get various transaction collision problems if these two threads access the server at the same time. I'm obviously missing something here--shouldn't different remote client threads from the same client be able to access JBoss simultaneously in the same way that entirely different clients can? I.e., shouldn't they spawn separate transactions which are scheduled appropriately by JBoss? Any clarification appreciated, Beau Cronin --- This SF.net email is sponsored by: Scholarships for Techies! Can't afford IT training? All 2003 ictp students receive scholarships. Get hands-on training in Microsoft, Cisco, Sun, Linux/UNIX, and more. www.ictp.com/training/sourceforge.asp ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user Try to do the same thing u are doing with 2 threads in the same VM, in 2 different JVMs. And (as I suspect it would be) if u get the same collisions (tx deadlocks?), your problem resides at the server side. Regards, Horia --- This SF.net email is sponsored by: Scholarships for Techies! Can't afford IT training? All 2003 ictp students receive scholarships. Get hands-on training in Microsoft, Cisco, Sun, Linux/UNIX, and more. www.ictp.com/training/sourceforge.asp ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
Re: [JBoss-user] Can two separate client threads make simultaneouscalls?
Are you hitting a Stateful Session Bean or a Stateless one? According to the EBJ spec, it is illegal to hit a transactional Stateful one from two threads simultaneously that have the same bean handle. David -- Beau Cronin escribió:: I have a Swing app which is essentially single-threaded, accessing the server in the usual way through a session facade. I'd like to do some background loading of certain data for performance reasons, but when I try to do this by using a separate thread (and separate session instance), I get various transaction collision problems if these two threads access the server at the same time. I'm obviously missing something here--shouldn't different remote client threads from the same client be able to access JBoss simultaneously in the same way that entirely different clients can? I.e., shouldn't they spawn separate transactions which are scheduled appropriately by JBoss? Any clarification appreciated, Beau Cronin --- This SF.net email is sponsored by: Scholarships for Techies! Can't afford IT training? All 2003 ictp students receive scholarships. Get hands-on training in Microsoft, Cisco, Sun, Linux/UNIX, and more. www.ictp.com/training/sourceforge.asp ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
