Oracle连接数过多释放机制

Oracle服务器连接数过多会当掉，把连接数过多的客户机网线拔出后，在远程Oracle上依然还会保留此用户的连接数，久久不能释放，上网查了下可以以下面方法解决。

通过profile可以对用户会话进行一定的限制，比如IDLE时间。
将IDLE超过一定时间的会话断开，可以减少数据库端的会话数量，减少资源耗用。

使用这些资源限制特性，需要设置resource_limit为TRUE：

[oracle@test126 udump]$ sqlplus "/ as sysdba"

SQL*Plus: Release 10.2.0.1.0 - Production on Fri Oct 13 07:58:21 2006

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

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning and Data Mining options

SQL> show parameter resource

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
resource_limit boolean TRUE
resource_manager_plan string

该参数可以动态修改：

SQL> alter system set resource_limit=true;

System altered.

数据库缺省的PROFILE设置为：

SQL> SELECT * FROM DBA_PROFILES;

PROFILE RESOURCE_NAME RESOURCE LIMIT
-------------------- -------------------------------- -------- ---------------
DEFAULT COMPOSITE_LIMIT KERNEL UNLIMITED
DEFAULT SESSIONS_PER_USER KERNEL UNLIMITED
DEFAULT CPU_PER_SESSION KERNEL UNLIMITED
DEFAULT CPU_PER_CALL KERNEL UNLIMITED
DEFAULT LOGICAL_READS_PER_SESSION KERNEL UNLIMITED
DEFAULT LOGICAL_READS_PER_CALL KERNEL UNLIMITED
DEFAULT IDLE_TIME KERNEL UNLIMITED
DEFAULT CONNECT_TIME KERNEL UNLIMITED
DEFAULT PRIVATE_SGA KERNEL UNLIMITED
DEFAULT FAILED_LOGIN_ATTEMPTS PASSWORD 10
DEFAULT PASSWORD_LIFE_TIME PASSWORD UNLIMITED

PROFILE RESOURCE_NAME RESOURCE LIMIT
-------------------- -------------------------------- -------- ---------------
DEFAULT PASSWORD_REUSE_TIME PASSWORD UNLIMITED
DEFAULT PASSWORD_REUSE_MAX PASSWORD UNLIMITED
DEFAULT PASSWORD_VERIFY_FUNCTION PASSWORD NULL
DEFAULT PASSWORD_LOCK_TIME PASSWORD UNLIMITED
DEFAULT PASSWORD_GRACE_TIME PASSWORD UNLIMITED

16 rows selected.

创建一个允许3分钟IDLE时间的PROFILE：

SQL> CREATE PROFILE KILLIDLE LIMIT IDLE_TIME 3;

Profile created.

新创建PROFILE的内容：

SQL> col limit for a10
SQL> select * from dba_profiles where profile='KILLIDLE';

PROFILE RESOURCE_NAME RESOURCE LIMIT
------------------------------ -------------------------------- -------- ----------
KILLIDLE COMPOSITE_LIMIT KERNEL DEFAULT
KILLIDLE SESSIONS_PER_USER KERNEL DEFAULT
KILLIDLE CPU_PER_SESSION KERNEL DEFAULT
KILLIDLE CPU_PER_CALL KERNEL DEFAULT
KILLIDLE LOGICAL_READS_PER_SESSION KERNEL DEFAULT
KILLIDLE LOGICAL_READS_PER_CALL KERNEL DEFAULT
KILLIDLE IDLE_TIME KERNEL 3
KILLIDLE CONNECT_TIME KERNEL DEFAULT
KILLIDLE PRIVATE_SGA KERNEL DEFAULT
KILLIDLE FAILED_LOGIN_ATTEMPTS PASSWORD DEFAULT
KILLIDLE PASSWORD_LIFE_TIME PASSWORD DEFAULT

PROFILE RESOURCE_NAME RESOURCE LIMIT
------------------------------ -------------------------------- -------- ----------
KILLIDLE PASSWORD_REUSE_TIME PASSWORD DEFAULT
KILLIDLE PASSWORD_REUSE_MAX PASSWORD DEFAULT
KILLIDLE PASSWORD_VERIFY_FUNCTION PASSWORD DEFAULT
KILLIDLE PASSWORD_LOCK_TIME PASSWORD DEFAULT
KILLIDLE PASSWORD_GRACE_TIME PASSWORD DEFAULT

16 rows selected.

测试用户：

SQL> select username,profile from dba_users where username='EYGLE';

USERNAME PROFILE
------------------------------ --------------------
EYGLE DEFAULT

修改eygle用户的PROFILE使用新建的PROFILE：

SQL> alter user eygle profile killidle;

User altered.

SQL> select username,profile from dba_users where username='EYGLE';

USERNAME PROFILE
------------------------------ --------------------
EYGLE KILLIDLE

进行连接测试：

[oracle@test126 admin]$ sqlplus eygle/eygle@eygle

SQL*Plus: Release 10.2.0.1.0 - Production on Fri Oct 13 08:07:13 2006
Copyright (c) 1982, 2005, Oracle. All rights reserved.

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning and Data Mining options

SQL> select username,profile from dba_users where username='EYGLE';

USERNAME PROFILE
------------------------------ ------------------------------
EYGLE KILLIDLE

当IDLE超过限制时间时，连接会被断开：
SQL> select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') from dual;

TO_CHAR(SYSDATE,'YY
-------------------
2006-10-13 08:08:41

SQL> select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') from dual;
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') from dual
*
ERROR at line 1:
ORA-02396: exceeded maximum idle time, please connect again