 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Java Forum / Databases / June 2004Regarding EJB accessing DB
Hi all, Please help:) I have a TaskManager class which is running as a timer, say every minute.In evenry minute, the TaskManager instantiates an EJB which makes a connection to the database and brings a file name which then will be loaded.When I run the application, I log the time in which timer is executed, and I see that the timer executes every one minute for some time and then suddenly there is a delay of 4-5 minutes.Again the timer comes back to normal and executes for sometime, again delays for 5-6 minutes. This happens sometimes, or not at all. What I am presuming is that when EJB is making a database connection using connection pool (we use WebLogic) , at a particluar time, EJB is not able to make a connection since all other connections may be in use and so waits for the next connection to be released. So by increasing the number of connections and no of EJBs will the problem be solved, please advise and thanks a lot for your time. Best regards, Suja > Hi all, > [quoted text clipped - 3 lines] > evenry minute, the TaskManager instantiates an EJB which makes a connection > to the database and brings a file name which then will be loaded. When you say 'instantiate', do you really mean 'create', or do you mean 'call'? See below for more questions... > When I run > the application, I log the time in which timer is executed, and I see that > the timer executes every one minute for some time and then suddenly there is > a delay of 4-5 minutes.Again the timer comes back to normal and executes for > sometime, again delays for 5-6 minutes. This happens sometimes, or not at > all. You should add code to see when the timer starts it's work, and when it finishes. If the timer doesn't start it's work sometimes for 6 minutes, it's a different problem than if the timer always starts, but sometimes doesn't finish for 6 minutes. > What I am presuming is that when EJB is making a database connection using > connection pool (we use WebLogic) , at a particluar time, EJB is not able to > make a connection since all other connections may be in use and so waits for > the next connection to be released. Typically weblogic does not let a requestor wait indefinitely for a pool connection. If the pool is fully used, a thread will typically wait no longer than 5 seconds. After that time, the requestor usually gets a ResourceException. > So by increasing the number of connections and no of EJBs will the problem > be solved, please advise and thanks a lot for your time. If you build your pool to have one connection for every execute-thread in the server, that is usually enough. If you find the server not running the timer code, or stuck running the timer code you should get a full server stacktrace to let us see what the server is doing. Joe Weinstein at BEA > Best regards, > Suja Hi Joe Weinstein, Thanks for the reply. To clarify: The timer starting time is delayed for some 4-5 minutes. It is not that timer is started and taking more time to finish.For example I am attaching the logs: 2004-06-21 18:08:59,665 DEBUG com.transeta.thb.util.ThubLogger - 2004-06-21 18:08:59,665 DEBUG com.transeta.thb.util.ThubLogger - TaskManager : Starting the ThubTaskManagerSession Bean Invocation at : 5/21/2004 18:8:59 2004-06-21 18:08:59,665 DEBUG com.transeta.thb.util.ThubLogger - TaskManager : Ending the ThubTaskManagerSession Bean Invocation at : 5/21/2004 18:8:59 2004-06-21 18:08:59,666 DEBUG com.transeta.thb.util.ThubLogger - 2004-06-21 18:09:59,665 DEBUG com.transeta.thb.util.ThubLogger - 2004-06-21 18:09:59,666 DEBUG com.transeta.thb.util.ThubLogger - TaskManager : Starting the ThubTaskManagerSession Bean Invocation at : 5/21/2004 18:9:59 2004-06-21 18:09:59,666 DEBUG com.transeta.thb.util.ThubLogger - TaskManager : Ending the ThubTaskManagerSession Bean Invocation at : 5/21/2004 18:9:59 2004-06-21 18:09:59,666 DEBUG com.transeta.thb.util.ThubLogger - 2004-06-21 18:10:59,665 DEBUG com.transeta.thb.util.ThubLogger - 2004-06-21 18:10:59,665 DEBUG com.transeta.thb.util.ThubLogger - TaskManager : Starting the ThubTaskManagerSession Bean Invocation at : 5/21/2004 18:10:59 2004-06-21 18:10:59,666 DEBUG com.transeta.thb.util.ThubLogger - TaskManager : Ending the ThubTaskManagerSession Bean Invocation at : 5/21/2004 18:10:59 2004-06-21 18:10:59,666 DEBUG com.transeta.thb.util.ThubLogger - 2004-06-21 18:11:59,665 DEBUG com.transeta.thb.util.ThubLogger - 2004-06-21 18:16:59,666 DEBUG com.transeta.thb.util.ThubLogger - TaskManager : Starting the ThubTaskManagerSession Bean Invocation at : 5/21/2004 18:16:59 2004-06-21 18:16:59,666 DEBUG com.transeta.thb.util.ThubLogger - TaskManager : Ending the ThubTaskManagerSession Bean Invocation at : 5/21/2004 18:16:59 PLEASE SEE THE LAST TWO LINES, 18.16 means there is a gap of five minutes. Any clue please, thanks a lot. Best regards, Ravi > > Hi all, > > [quoted text clipped - 43 lines] > This message was checked by NOD32 Antivirus System. > http://www.nod32.com > Hi Joe Weinstein, > [quoted text clipped - 4 lines] > The timer starting time is delayed for some 4-5 minutes. It is not that > timer is started and taking more time to finish. > One more clue. I just wrote a System.out.println in the EJB instead of making a connection to the database. The logs are perfect, I mean every one minute, no discrepancies. I don't completely understand... If the EJB is called by the timer, how can the EJB get called every minute, but the timer get delayed? In any case, if the timer is getting delayed, it sounds like a problem with the timer. When the timer is delayed, are you sure the previous timer had finished it's work within the minute before the next one was supposed to start? If so, this seems like a JVM/timer problem, nothing to do with JDBC or the DBMS... Joe Weinstein at BEA For example I am attaching > the logs: > [quoted text clipped - 134 lines] >>This message was checked by NOD32 Antivirus System. >>http://www.nod32.com Hi Jon, One more clue. I just wrote a System.out.println in the EJB instead of making a connection to the database. The logs are perfect, I mean every one minute, no discrepancies. Can we conclude anything, thanks Best Regards, Ravi > > Hi all, > > [quoted text clipped - 43 lines] > This message was checked by NOD32 Antivirus System. > http://www.nod32.com >One more clue. I just wrote a System.out.println in the EJB instead of >making a connection to the database. The logs are perfect, I mean every one >minute, no discrepancies. > >Can we conclude anything, thanks Your timer spawns some task on cue. For some reason that task is stalling.  SignatureCanadian Mind Products, Roedy Green. Coaching, problem solving, economical contract programming. See http://mindprod.com/jgloss/jgloss.html for The Java Glossary. Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
|
Reply to this Message
|
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.