I did a Google search on "jk2_channel_apr_send send failed 32 Broken pipe" and found this web page that discusses the error. Once you navigate to the page, search for the error (it's at the bottom of the page). Here's the relevant quote:
Apache Tomcat Connector
If you see the following error messages in your apache error.log:
[Wed May 03 14:56:21 2006] [error] jk2_channel_apr_send send failed 32 Broken pipe
[Wed May 03 14:56:21 2006] [error] ajp13.service() Error sending initial post -3 32 0
and you may also see the following messages in you catalina.out:
May 3, 2006 2:57:15 PM org.apache.jk.common.ChannelSocket processConnection
INFO: connection timeout reached Then these messages belong together. In standard configuration the connection(s) between apache threads / processes and tomcat get closed after a timeout of 20s. To avoid these messages and keep the connection(s) persistent you have to edit /etc/tomcat4/system.xml (or where ever it resides on your system). You have to set a connectionTimout of 0 in connector configuration for port 8900.