在RAC系统的DIAG TRACE文件中发现了标题中的信息，全部的日志信息如下：
Switch to short timeout for ipc polling
a session (kjzha) is registered
session (kjzha) is about to end
Registered session (kjzha)[11][4][0][1] is cleaned up
Switch to long timeout for ipc polling[@more@]

在GOOGLE中找到一遍有头没尾的文章，中间提到说因为ORACLE的心跳之前通信是通过UDP方式实现的，而UDP就是使用IPC方式来实现的，所以应该查看IPC相关的设置，不过是个太监贴。

跑到METALINK，找了半天也没有很吻合的，只找到了ML:750773.1，大概是说这个东西从10.1版本就有了，但是到11.6就非常多了，是一个UNPUBLISHED BUG。
Cause
This is unpublished Bug 6678289 'EXCESSIVE DIA0 TRACE FILES IN A RAC ENVIRONMENT'

This causes unconditional writing of trace output to DIAG and LMON trace files in versions from 10.1 onwards. It is most commonly seen in 11.1.0.6, however.
Solution

* Upgrade to 11.1.0.7 where the problem has been fixed
* One-off patches have been created on some platforms on top of 11.1.0.6. Check Patch 6678289 to see if there is one available for your platform.