Oracle体系结构及备份（十三）——bg-pmon

一 什么是PMON进程

 

        The process monitor performs processrecovery when a user process fails. PMON is responsible for cleaning up thecache and freeing resources that the process was using. PMON also checks on thedispatcher processes (described later in this table) and server processes andrestarts them if they have failed.

 

        PMON，进程监控进程（动态注册监听器）

 

        作用：

                清除失败的进程

                回滚事务

                释放锁

                释放其他资源

                重启死掉的Dispatchers

 

二 操作示例

oracle@localhost 桌面]$  ps -ef | grep ora_ | grep pmon
oracle    2889     1  0 17:01 ?        00:00:00 ora_pmon_orcl
[oracle@localhost 桌面]$ kill -9 2889
[oracle@localhost 桌面]$  ps -ef | grep ora_ | grep pmon
[oracle@localhost 桌面]$  ps -ef | grep ora_
oracle    2950  2597  0 17:05 pts/0    00:00:00 grep ora_
[oracle@localhost 桌面]$  ps -ef | grep ora_ | grep pmon
[oracle@localhost 桌面]$ sqlplus / as sysdba;

SQL*Plus: Release 10.2.0.1.0 - Production on Tue Jun 4 17:05:59 2013

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> conn scott/tiger;
ERROR:
ORA-01034: ORACLE not available
ORA-27101: shared memory realm does not exist
Linux Error: 2: No such file or directory


Warning: You are no longer connected to ORACLE.
SQL> conn / as sysdba;
Connected to an idle instance.
SQL> exit;
Disconnected
[oracle@localhost 桌面]$  ps -ef | grep ora_
oracle    2963  2597  0 17:06 pts/0    00:00:00 grep ora_
[oracle@localhost 桌面]$ startup
bash: startup: command not found
[oracle@localhost 桌面]$ sqlplus / as sysdba;

SQL*Plus: Release 10.2.0.1.0 - Production on Tue Jun 4 17:07:01 2013

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup
ORACLE instance started.

Total System Global Area  838860800 bytes
Fixed Size		    1222192 bytes
Variable Size		  775948752 bytes
Database Buffers	   58720256 bytes
Redo Buffers		    2969600 bytes
Database mounted.
Database opened.

SQL> conn scott/tiger;
Connected.
SQL> exit;
Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
[oracle@localhost 桌面]$  ps -ef | grep ora_
oracle    2968     1  0 17:07 ?        00:00:00 ora_pmon_orcl
oracle    2970     1  0 17:07 ?        00:00:00 ora_psp0_orcl
oracle    2972     1  0 17:07 ?        00:00:00 ora_mman_orcl
oracle    2974     1  0 17:07 ?        00:00:00 ora_dbw0_orcl
oracle    2976     1  0 17:07 ?        00:00:00 ora_lgwr_orcl
oracle    2978     1  0 17:07 ?        00:00:00 ora_ckpt_orcl
oracle    2980     1  0 17:07 ?        00:00:00 ora_smon_orcl
oracle    2982     1  0 17:07 ?        00:00:00 ora_reco_orcl
oracle    2984     1  0 17:07 ?        00:00:00 ora_cjq0_orcl
oracle    2986     1  1 17:07 ?        00:00:00 ora_mmon_orcl
oracle    2988     1  0 17:07 ?        00:00:00 ora_mmnl_orcl
oracle    2990     1  0 17:07 ?        00:00:00 ora_d000_orcl
oracle    2992     1  0 17:07 ?        00:00:00 ora_s000_orcl
oracle    2996     1  0 17:07 ?        00:00:00 ora_qmnc_orcl
oracle    2998     1  2 17:07 ?        00:00:00 ora_j000_orcl
oracle    3004     1  0 17:07 ?        00:00:00 ora_q000_orcl
oracle    3006     1  0 17:07 ?        00:00:00 ora_q001_orcl
oracle    3009  2597  0 17:07 pts/0    00:00:00 grep ora_
[oracle@localhost 桌面]$  ps -ef | grep ora_ | grep pmon
oracle    2968     1  0 17:07 ?        00:00:00 ora_pmon_orcl

三 总结

        1. PMON，进程监控进程，动态注册监听器。

        2.作用：清除失败的进程、回滚事务、释放锁、释放其他资源、重启死掉的Dispatchers。

        3.Linux下仍然采用ps命令查看。

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  By Larry Wen

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