第一章??Oracle hang 之sqlplus -prelim使用方法?

很多情況下，Oracle hang導致sqlplus無法連接，從而無法獲得Oracle系統和進程狀態，使得定位問題缺少強有力的依據。所幸的是Oracle 10g推出了sqlplus -prelim選項，在Oracle掛起時依然能使用sqlplus，從而能獲得數據庫狀態。
使用方法如下

引用

$ sqlplus -prelim "/as sysdba"

SQL*Plus: Release 10.2.0.4.0 - Production on Sun Mar 28 06:40:21 2010

Copyright (c) 1982, 2007, Oracle.? All Rights Reserved.

在prelim模式下，不可以查詢數據字典,但可以關閉數據庫

引用

SQL> select status from v$instance;
select status from v$instance
*
ERROR at line 1:
ORA-01012: not logged on

?

引用

SQL> shutdown abort
ORACLE instance shut down.

但可以使用oradebug，但對于系統診斷，已經足夠了
dump系統狀態

引用

SQL> oradebug setmypid????????????????????????????????????????????
Statement processed.
SQL> oradebug unlimit
Statement processed.
SQL> oradebug dump systemstate 266
Statement processed.

或者dump hanganalyze

引用

SQL> oradebug? hanganalyze 3
Hang Analysis in /oracle/app/oracle/admin/ora10g/udump/ora10g_ora_52642.trc

對于rac

引用

SQLPLUS> oradebug setmypid

SQLPLUS>oradebug setinst all

SQLPLUS>oradebug -g def hanganalyze 3

或者dump 進程狀態

引用

SQL> oradebug dump processstate 10
Statement processed.

進一步，如果有10g客戶端，數據庫是9i，依然可以用-prelim

引用

$ sqlplus -prelim /nolog

SQL*Plus: Release 10.2.0.4.0 - Production on Sun Mar 28 06:50:19 2010

Copyright (c) 1982, 2007, Oracle.? All Rights Reserved.

SQL> conn sys/oracle@ora9i as sysdba
Prelim connection established
SQL>? oradebug setmypid
Statement processed.
SQL> oradebug unlimit
Statement processed.
SQL>? oradebug dump systemstate 266
Statement processed.

?

There are two ways to connect to sqlplus using a preliminary connection.

1.?sqlplus -prelim / as sysdba

2.?sqlplus /nolog
set _prelim on
connect / as sysdba

?

1. While running system state dump with "-prelim" option:

sqlplus -prelim / as sysdba

SQL*Plus: Release 10.2.0.2.0 - Production on Mon Dec 11 17:28:14 2006

SQL> oradebug setmypid
Statement processed.
SQL> oradebug unlimit
Statement processed.
SQL> oradebug dump systemstate 266
ORA-03113: end-of-file on communication channel
ORA-24323: value not allowed

?

2. The following error is reported in the alert.log:

ORA-07445: exception encountered: core dump [kgllkd()+1254] [SIGSEGV] [Address not mapped to
object] [0x000000030] [] []

The error did not crash background process or terminate the instance.

?

The issue is not resolved in any known patches.

Use any of the below workarounds:

·?Connect / as sysdba (without -prelim)

OR

·?Force the variable PGA to be initialized:

?

sqlplus -prelim '/ as sysdba'
oradebug setmypid
oradebug unlimit
oradebug call ksmcpg
oradebug dump systemstate 10

--測試環境11g,獲lgwr的spid
SQL> select * from v$process where username='SYSTEM' and program like '%LGWR%';
?
ADDR??????????????????? PID SPID???????????????????? PNAME USERNAME?????????? SERIAL# TERMINAL???????? PROGRAM????????????????????????????????????????????????????????? TRACEID????????????????????????????????????????????????????????????????????????? TRACEFILE??????????????????????????????????????????????????????????????????????? BACKGROUND LATCHWAIT??????? LATCHSPIN??????? PGA_USED_MEM PGA_ALLOC_MEM PGA_FREEABLE_MEM PGA_MAX_MEM
---------------- ---------- ------------------------ ----- --------------- ---------- ---------------- ---------------------------------------------------------------- -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- ---------- ---------------- ---------------- ------------ ------------- ---------------- -----------
000007FF614CD768???????? 11 17428??????????????????? LGWR? SYSTEM?????????????????? 1 123-PC?????????? ORACLE.EXE (LGWR)???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? d:\oracle11g_64bit\diag\rdbms\second\second\trace\second_lgwr_17428.trc????????? 1???????????????????????????????????????????????? 5007762?????? 5465314?????????? 131072???? 9921762

--另啟一會話窗口,暫掛lgwr進程
SQL> oradebug setsospid 17428
ORA-00070: command setsospid is not valid
SQL> oradebug setospid 17428
Oracle pid: 11, Windows thread id: 17428, image: ORACLE.EXE (LGWR)
SQL> oradebug suspend
Statement processed.

--發生日志切換hang住
SQL> alter system switch logfile;
?
System altered
--新建一個會話窗口
create table t_h(a int);--語句hang住

--解掛lgwr進程,上述lgwr及create操作順利執行完畢
SQL> oradebug resume
Statement processed.

小結：如果日志切換時,會暫住一切所有的數據庫前端事務create and dml

?

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