oracle12542,ora-12542（Windows2003下 Oracle监听器启动后自动关闭）

今天发现Windows 2003server上的Oracle 监听器无法启动，在Windows服务里启动后立即停止，在cmd环境下执行lsnrctl start命令会报ora-12542错误。

实际上以上监听器异常现象在前几天偶尔出现，后来监听器端口被占用原因，应用系统所对应的数据库用户无法链接数据库。

处理过程：

1、重建监听器没有用，重启服务器后也是没法连接数据库(sys / as sysdba可以连接，并可以正常启动和关闭数据库)；

2、因数据库小，因此先备份(expdp)好数据后重新安装Oracle并重建数据库，还是不行。[@more@]

3、以上方法都失败后，我开始搜索网络，如下是从中得到metalink解答内容，解释很好：

Cause

Problem is caused due to the fact that the free ports in the windows client has been exhausted and it is trying to make use of a port which is in TIME_WAIT state which gives the error TNS-12542: Address already in use.

Solution

There are 2 solutions available:

1.) Increase the free port range:

======================

Start Registry Editor (Regedt32.exe).

Locate the following key in the registry:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesTcpipParameters

On the Edit menu, click Add Value, and then add the following registry value:

Value Name: MaxUserPort Data Type: REG_DWORD Value: 65534

Valid Range: 5000-65534 (decimal) Default: 0x1388 (5000 decimal)

Description: This parameter controls the maximum port number used when an application requests any available user port from the system. Normally, ephemeral (that is, short-lived) ports are allocated between the values of 1024 and 5000 inclusive.

2.) Decrease the value for TIME_WAIT state:

================================

TcpTimedWaitDelay (new in Windows NT versions 3.51 SP5 and later)

Key: TcpipParameters

Value Type: REG_DWORD - Time in seconds

Valid Range: 30-300 (decimal)

Default: 0xF0 (240 decimal)

Description: This parameter determines the length of time that a connection will stay in the TIME_WAIT state when being closed. While a connection is in the TIME_WAIT state, the socket pair cannot be re- used. This is also known as the "2MSL" state, as by RFC the value should be twice the maximum segment lifetime on the network. See RFC793 for further details.

这主要是由于操作系统的临时端口不够用而引起的。一般系统的临时端口为 1024-5000，这在多用户的环境下，3000多个oracle链接就用光了。由于每个链接断开以后，还要有一个等待时间，例如在 windows 系统中，这个时间是 120秒。

这就导致了一个现象：一会可以联通，一会又出现ora-12542 address in used。如果有临时端口可以使用，可以联通oracle；如果暂时端口没有了，就连不通了。

一下是在windows系统下的解决办法。

1、进入注册表编辑器(regedit)，在 HKEY_LOCAL_MACHINEsystemCurrentControlSetServicesTcpipParameters 里，编译-> 添加-> MaxUserPort (类型 REG_DWORD ), 值中填写 65534,(十进制，可以的范围是5000-65534).

2、退出 注册表编辑器,重新启动机器.