SQL*NET SESSION의 DEAD CONNECTION 처리 방법

Question

제품 : SQL*NET
작성날짜 : 1996-04-03
SQL*NET SESSION의 DEAD CONNECTION 처리 방법
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server에서 수행 중이던 프로그램이 비정상 종료한 경우에는 오라클의 smon이
자동으로 detection하여 수행 중이던 transaction을 rollback하여
정리하여 준다.
그러나, Client Server 환경에서 PC를 Client로 사용 시 비정상적인 방법으로
Server와 Disconnect 하면 Server 쪽에 있는 Dedicated Server가 남아 있다.
이는 Sql*net V1 & V2에서 발생하던 문제로 Sql*net V2.1 이후에는 아래와
같은 방법을 이용하면 Dead connection이 정상적으로 Disconnect 된다.
* 환경 : Server - Sql*net tcp/ip V2.1.3
Client - Sql*net V2.0
* Setup 방법 : Server와 Client에 있는
$ORACLE_HOME/network/admin/sqlnet.ora에
sqlnet.expire_time=n
으로 setting 한다.
여기서 n은 분 단위이며 실제 disconnect는 n분보다 더 걸린다.
일반적으로 sqlnet.expire_time=1로 설정하면 적당하다.

Answer 1

Hi,
Probe send - client and application still there - all fine
Network cable on the client is removedAt the above stage if the Sever sents a probe then if does not receive any message from Client it is treated as DCD. (It will receive any error code or negative response from client instead of any active status communication)
Application is shut down
(Optionally the computer is rebooted)
Network cable is reattached
Next probe send from server
At this point, the client is reachable, the Oracle NET component on the client is there, but the application on the client is gone without properly saying good bye to the DB server.
Would DCD detect the dead connection in this sceanrio?If my above comment is dismissed and your case or assumptions continues, then we need to check the SQL_EXPIRE time which you have connected. If the every thing happens with in the time setted for Expire time then, still it will treat as DCD, your session is getting terminated the system got rebooted.
You understanding with DCD is correct.
We see sessions in V$SESSIONS that don't have a process on the client any more. We have SQLNET.EXPIRE_TIME set to 2 minutes on the server, but still these sessions show up after days. Sessions show up as inactive and are waiting on "SQL*NET message from client" for hours and days.See basically INACTIVE and DCD are different. Slight difference exits. As you said you find inactive sessions. If you want to cleanup those inactive sessions, as per oracle documenation, you can create a custom profile as per your requrement and assign some IDLE_TIME and update the respective user profile. That might help you out.
- Pavan Kumar N