Thanx for the answer. Of course i can get deadlocks as i work against a database - but this deadlock seems to be caused by orion itself prior of accessing the database. Orion must have some internal locking mechanisms to avoid concurrent access to entity bean variables, i assume. And the 'resource entity's mentioned in the exception are orion specific and have nothing to do with my database (which i update myself via BMP). I'd like to know if orion's isolation level "repeatable_read" is equivalent to someting like "exclusive read" (which would avoid any deadlocks if the data gets locked for read and write until the end of a transaction). Furthermore the setting of "max-tx-retries" would help repeating a failed exception, but i did not get it work. Regards, Jens Stutte -----Ursprüngliche Nachricht----- Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Gesendet am: Montag, 26. Juni 2000 14:48 An: [EMAIL PROTECTED] Betreff: RE: DeadlockException Hi! The short answare is that it's your fault. You can get deadlocks in everyform of applications working against a database. And as a result of some applications sharing the same database and taking out locks in the database blocking each other. Deadlocks are a commen problem when one are developing applications for big shared database. One should always handle them. A few tips for programming against a database in general: Keep locks as little as possible. Always use transaction around updates. For ejb there are som extra rules. Recomended reading for you is: http://java.sun.com/j2ee/j2sdkee/techdocs/guides/ejb/html/DevGuideTOC.html I would also recomend you to read about programing 2-tier database applications as the same principals apply to programming in a j2ee enviorments. You are just adding some design rules as this is a 3-tier enviorment. As a rule of tomb always use a Session bean to access a entitybean. Never access them directly. Let your buisness logic in the sessionbeans take care of the transaction logic. In your case from the stacktrace you have two different connections to orion that simutaniously are trying to update the same database row or rows on the same page. (Depending on your databaseserver) As I see from the stacktrace you are doing an update. Do you remember dataintegrety? An easy tip is to add a timestamp to table and check against it if you are doing an update. If it has changed do a rolback and give the user an error about that the data has changed. If you get a rolback because of a deadlock just try to do the opperation again, but remember to have this test. Regards, Torgeir -----Original Message----- From: Jens Stutte [mailto:[EMAIL PROTECTED]] Sent: 26. juni 2000 13:37 To: Orion-Interest Cc: '[EMAIL PROTECTED]' Subject: DeadlockException Hi, i'm not sure, if this could be a bug, but often concurrent access to my beans lead to the following Exception: com.evermind.server.rmi.OrionRemoteException: Transaction was rolled back: thread 5 is waiting for resource entity 28417 in Site held by thread 6 in transaction [Transaction 85:0:0:0:0:0:0:0:0:df:0:df:fc:c2:ea:4b] who is waiting for resource entity 29185 in Site held by thread 5 in transaction [Transaction 83:0:0:0:0:0:0:0:0:df:0:df:fc:c2:ea:10] at EntityBeanWrapper0.setText(EntityBeanWrapper0.java, Compiled Code) at java.lang.reflect.Method.invoke(Native Method) at com.evermind.server.rmi.ba.run(JAX) at com.evermind.server.rmi.a8.gu(JAX, Compiled Code) at com.evermind.server.rmi.a8.run(JAX, Compiled Code) at com.evermind.util.e.run(JAX, Compiled Code) at connection to beatnix.net-media.de/10.0.1.13 as admin at com.evermind.server.rmi.a8.invokeMethod(JAX) at com.evermind.server.rmi.a_.invoke(JAX) at __Proxy3.setText(Unknown Source) at de.netmedia.ejb.test.clienttest.addWords(clienttest.java:113) at de.netmedia.ejb.test.clienttest.main(clienttest.java:271) Nested exception is: com.evermind.server.DeadlockException: thread 5 is waiting for resource entity 28417 in Site held by thread 6 in transaction [Transaction 85:0:0:0:0:0:0:0:0:df:0:df:fc:c2:ea:4b] who is waiting for resource entity 29185 in Site held by thread 5 in transaction [Transaction 83:0:0:0:0:0:0:0:0:df:0:df:fc:c2:ea:10] at com.evermind.server.ejb.AbstractEJBObject.startCall(JAX) at EntityBeanWrapper4.addEntry(EntityBeanWrapper4.java, Compiled Code) at de.netmedia.ejb.base.accesshashbean.NMejbAccessHashBean.addEntry(NMejbAccess HashBean.java, Compiled Code) at StatelessSessionBeanWrapper16.addEntry(StatelessSessionBeanWrapper16.java, Compiled Code) at de.netmedia.ejb.interfaces.server.NMejbString.addToHash(NMejbString.java, Compiled Code) at de.netmedia.ejb.interfaces.server.NMejbValue.set(NMejbValue.java, Compiled Code) at de.netmedia.ejb.interfaces.server.NMejbString.set(NMejbString.java, Compiled Code) at de.netmedia.ejb.base.basebean.NMejbBaseBean.setValueIntern(NMejbBaseBean.jav a, Compiled Code) at de.netmedia.ejb.base.basebean.NMejbBaseBean.setValue(NMejbBaseBean.java, Compiled Code) at de.netmedia.ejb.base.binarybean.NMejbBinaryBean.setText(NMejbBinaryBean.java , Compiled Code) at EntityBeanWrapper0.setText(EntityBeanWrapper0.java, Compiled Code) at java.lang.reflect.Method.invoke(Native Method) at com.evermind.server.rmi.ba.run(JAX) at com.evermind.server.rmi.a8.gu(JAX, Compiled Code) at com.evermind.server.rmi.a8.run(JAX, Compiled Code) at com.evermind.util.e.run(JAX, Compiled Code) at connection to beatnix.net-media.de/10.0.1.13 at com.evermind.server.rmi.OrionRemoteException.gy(JAX) at com.evermind.server.rmi.a8.gr(JAX) at com.evermind.server.rmi.a8.run(JAX) at java.lang.Thread.run(Thread.java:484) Is this a programming issue, that is, my fault? And if so, how do i get information on what's going wrong? Or (as i hope ;-) should orion assure that there will be no deadlocks of this kind? Note that i set the isolation level to "repeatable_read". Regards, Jens Stutte PS: My last few postings did not recieve any answer, if my questions are stupid or annoying or if i should register (and pay) for further support, please let me know. ____________________________________________ [EMAIL PROTECTED], http://www.netmedia.de NetMedia GmbH Neugrabenweg 5-7 66123 Saarbruecken Germany fon: +49 (0) 681 - 3 79 88 - 0 fax: +49 (0) 681 - 3 79 88 - 99
