apache httpd hung in "W" Sending Reply

[Nicholas Ide <id...@lhc.nlm.nih.gov>]

I have tomcat 4.1.27 front ended by apache 2.0.47 and mod_jk connector.

Occasionally I run out of apache slots because all the slots are
apparently hung while Sending Reply.  (W status from serverstatus screen).
These connections appear to all be stuck in a dialog with tomcat.
If I restart tomcat then apache cleans up the slots.

I cannot reproduce the problem myself.  I simply have to wait long
enough, perhaps 48 hours, for the planets to align and cause the problem.
I am unable to detect a pattern for the failures.
They also happened under tomcat 4.0.4 and apache 1.3.26.

Is there a configuration parameter on *either* the apache or tomcat 
side which will REALLY time out such hanging connections?
The "connectionTimeout" parameter in the Connector apparently
does not do the trick.  Nor does the soTimeout or serverTimeout
parameters found in jk2.properties.

Snippet from server.xml:

    <Connector className="org.apache.coyote.tomcat4.CoyoteConnector"
       port="@CATALINA_AJP_PORT@" minProcessors="10" 
       maxProcessors="85"
       enableLookups="false" redirectPort="8443"
       acceptCount="10" debug="0" 
       connectionTimeout="10000"
       useURIValidationHack="false"
       protocolHandlerClassName="org.apache.jk.server.JkCoyoteHandler"/>

jk2.properties:

     channelSocket.port=@CATALINA_AJP_PORT@
     channelSocket.scheme=http
     channelSocket.soTimeout=50000

Configuration:
 CoyoteConnector with JkCoyoteHandler
 Catalina 4.1.27-LD-jdk14
 Apache/2.0.47 (Unix) mod_jk/1.2.1
 SunOS 5.8 
 

-Nick