Thanks Dan/Krish . I was not able to get any valuable info so far . For time being I have suggested to enable the listener logging with trace_level_client=16 and wait for the next occurrance. I heard that they have a similar issue before 2 months . so hopefully I will be able to catch it the next time by following both of your suggestion.. Thanks -Prasad On Fri, Apr 18, 2008 at 4:26 PM, Dan Norris <dannorris@xxxxxxxxxxxxx> wrote: > If restarting the listener "fixed" the problem, then I'd have to believe > that your issue was either related to networking issues on the DB server, > the listener process somehow became unresponsive, or your dispatcher(s) > became unresponsive. The only way to investigate would be to reproduce the > issue with SQL*Net tracing on (trace_level_client=16) and see what's in the > trace. > > It might also be interesting to know how many connection requests the > listener is servicing. I suppose it's possible that the tcp queuedepth is > too small to handle all the requests if there some some sort of a login > storm or something. Without listener logging enabled, you'd only be able to > check v$sysstat (where name = 'logons cumulative') periodically to see how > many logins are occurring. Statspack should also be gathering that > information, so consult there for historical purposes. > > Dan > > > Prasad wrote: > > On 17/04/2008, *Prasad* <p4cldba@xxxxxxxxx> wrote: > > > > Greetings. > > > > This was something that happened today in one of the database and I am > > looking for list's > > response on this. This is a Oracle 9.2.0.7 database running solaris 9. > > > > Around 10am the Unix group called me and told me that one of the > > osprocess is taking more cputime > > then what it normally takes. and upon investigation I found that this > > database was running on > > shared server mode with the osprocess being the only dispatcher at that > > time . So I created another > > 3 dispatcher and stopped the existing dispatcher d000. > > > > and everything was going fine until 2.30pm when the user called me and > > told me that he is not able to > > make connection using servicename. so I did a test > > > > test1- sqlplus '/as sysdba' > > test2- sqlplus scott/tiger > > test3- sqlplus scott/tiger@tnsname > > > > > > I was able to logon to database successfully with test1 and test2 . > > However when I did test3 > > it just hangs and it didnt allow me to interrupt it also. > > > > I checked if the dispatchers were busy or not and didnt found anything > > significant. > > The listener logging was not enabled so the initial reaction was to > > shutdown and start the > > listener which I did and at this time the test3 worked fine . However > > the user was still not able to > > access its application and I observed a large number of session in > > dba_blocker and dba_waiter > > and also few deadlock error in alert log file . So I killed the session > > on the beginning of the queue > > and it immediately releases all the sessions in dba_blockers and > > dba_waiters and the user was > > able to access the application. > > > > Here comes the hard part what is the root cause of this issue? > > > > Please advise. > > > > Thanks > > -Prasad > > > >