今天看到一个帖子

在LISTENER.LOG中发现如下错误：

WARNING: Subscription node down event still pending

METALINK：Note:372959.1中有详细的描述

Applies to:

Oracle Net Services - Version: 10.1.0.2 to 10.2.0.2
This problem can occur on any platform.

Symptoms

You are receiving the following warning messages in the listener.log file constantly since upgraded the TNS Listener from 9.2.0.7 to 10.2.0.2:

'WARNING: Subscription for node down event still pending' 

Changes

Upgraded the TNS Listener from 10.2.0.2.0

Cause

These messages are related to the Oracle10g TNS Listener's default subscription to the Oracle Notification Service (ONS). In a non-RAC environment it is recommended to disable this subscription.

Solution

Set the following parameter in the listener.ora:

SUBSCRIBE_FOR_NODE_DOWN_EVENT_=OFF

Where should be replaced with the actual listener name configured in the
LISTENER.ORA file.

SUBSCRIBE_FOR_NODE_DOWN_EVENT_ parameter is to be placed by istelf on an empty line.

This will prevent the messages from being written to the log file, but also prevent the 10g TNS
Listener from hanging periodically.

Please Note: Setting SUBSCRIBE_FOR_NODE_DOWN_EVENT to OFF disable some RAC functionality. The above workaround is valid only for non-RAC environments.
The issue is present on all 10g versions.