DeadLock: session wait on itself with no rows.

hi, friends:                 

>>>select count(*) into :b0 from USERCONFIRMINFO where USER_ID=:b1
>>>The following deadlock is not an ORACLE error. It is a
>>>deadlock due to user error in the design of an application
>>>or from issuing incorrect ad-hoc SQL. The following
>>>information may aid in determining the deadlock:
>>>
>>>Deadlock graph:
>>>---------Blocker(s)-------- ---------Waiter(s)---------
>>>Resource Name process session holds waits process session holds waits
>>>TX-000e005d-00037cfa 306 484 X 306 484 S
>>>session 484: DID 0001-0165-00010802 session 484: DID 0001-0165-00010802
>>>Rows waited on:
>>>Session 484: no row
 

Another trace file like:
>>>*** 2003-03-02 16:50:22.447
>>>DEADLOCK DETECTED
>>>Current SQL statement for this session:
>>>select USER_ID ,USER_EMAIL into :b0,:b1 from USERPRIVATEINFO where USER_ACCOUNT=:b2
>>>The following deadlock is not an ORACLE error. It is a
>>>deadlock due to user error in the design of an application
>>>or from issuing incorrect ad-hoc SQL. The following
>>>information may aid in determining the deadlock:
>>>Deadlock graph:
>>> ---------Blocker(s)-------- ---------Waiter(s)---------
>>>Resource Name process session holds waits process session holds waits
>>>TX-0012004a-000374f8 293 263 X 306 512 S
>>>session 263: DID 0001-0165-0004EC65 session 512: DID 0001-0165-0004EC65
>>>Rows waited on:
>>>Session 512: no row

I ever saw message talking about two session deadlock with no rows waited on, maybe it is because of pctfree/initrans, How about session wait on itself then? And how can it happen?

Regards
zhu chao
msn:chao_ping_at_163.com
www.happyit.net
www.cnoug.org(China Oracle User Group)

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Author: chao_ping
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