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【学习笔记】Oracle oradebug 操作会话的使用案例

时间:2016-07-23 10:25   来源:Oracle研究中心   作者:惜分飞   点击:

天萃荷净 使用oradebug hang住某个进程,通过oradebug SUSPEND来实现多次redo切换而这些redo并未被归档的情景

在一次测试中,需要模拟在归档模式下,数据库发生多次redo切换而这些redo并未被归档的情景,一般来说这样的情况只有在归档目录满的时候会遇到.但是在日常测试中,这样的归档目录满的模拟不太现实,可以通过oradebug SUSPEND来实现该功能,让arcn进程挂起
配置log_archive_max_processes为1(可以配置多个,但是1个更加方便测试)

SQL> show parameter log_archive_max_processes;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
log_archive_max_processes            integer     1

该配置可以在线修改,但是不重启数据库不一定完全生效(测试环境本来是4,修改为1之后,还有arc0和arc1进程)

查找arcn进程

[oracle@localhost trace]$ ps -ef|grep ora_arc
oracle    3686     1  0 21:07 ?        00:00:00 ora_arc0_test

oradebug进程(session 1)

SQL> oradebug  setospid  3686
Oracle pid: 57, Unix process pid: 3686, image: oracle@localhost.localdomain (ARC0)
SQL> oradebug SUSPEND
Statement processed.

alert日志

Tue Apr 16 21:09:42 2013
Unix process pid: 3686, image: oracle@localhost.localdomain (ARC0) flash frozen [ command #1 ]

切换日志(session 2)

SQL> archive log list;
Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     53
Next log sequence to archive   55
Current log sequence           55
SQL> alter system switch logfile;

System altered.

SQL> /

System altered.

SQL> alter system checkpoint;

System altered.

SQL> set lines 134
SQL> col member for a40
SQL>   SELECT thread#,
  2           a.sequence#,a.ARCHIVED,
  3           a.group#,
  4           TO_CHAR (first_change#, '9999999999999999') "SCN",
  5           a.status,
  6           MEMBER
  7      FROM v$log a, v$logfile b
  8     WHERE a.group# = B.GROUP#
  9  ORDER BY a.sequence# DESC;

   THREAD#  SEQUENCE# ARC     GROUP# SCN               STATUS           MEMBER
---------- ---------- --- ---------- ----------------- ---------------- ----------------------------
         1         57 NO           3            261053 CURRENT          /data/oracle/oradata/test/redo03.log
         1         56 NO           2            261046 INACTIVE         /data/oracle/oradata/test/redo02.log
         1         55 NO           1            260856 INACTIVE         /data/oracle/oradata/test/redo01.log

SQL> alter system switch logfile;--hang住

此时alert日志

Tue Apr 16 21:10:19 2013
Thread 1 advanced to log sequence 56 (LGWR switch)
  Current log# 2 seq# 56 mem# 0: /data/oracle/oradata/test/redo02.log
Tue Apr 16 21:10:36 2013
Thread 1 advanced to log sequence 57 (LGWR switch)
  Current log# 3 seq# 57 mem# 0: /data/oracle/oradata/test/redo03.log

Tue Apr 16 21:13:13 2013
ORACLE Instance test - Can not allocate log, archival required
Thread 1 cannot allocate new log, sequence 58
All online logs needed archiving
  Current log# 3 seq# 57 mem# 0: /data/oracle/oradata/test/redo03.log

oradebug RESUME(session 1)

SQL> oradebug RESUME  
Statement processed.

alert日志

Tue Apr 16 21:14:23 2013
Unix process pid: 3686, image: oracle@localhost.localdomain (ARC0) resumed
Archived Log entry 2 added for thread 1 sequence 55 ID 0x7dd4ccb7 dest 1:
Archived Log entry 3 added for thread 1 sequence 56 ID 0x7dd4ccb7 dest 1:

hang住会话继续执行(session 2)

SQL> alter system switch logfile;

System altered.

--------------------------------------ORACLE-DBA----------------------------------------

最权威、专业的Oracle案例资源汇总之【学习笔记】Oracle oradebug 操作会话的使用案例

本文由大师惜分飞原创分享,网址:http://www.oracleplus.net/arch/843.html

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