[users@httpd] Apache 2.0.52 / server status / connection stuck in "..Reading.."

[pt...@intec.ugent.be]

Hello,

We're running Apache 2.0.52 on RHEL 4.6 with mod_ssl. Recently, we had to
significantly increase our Apache Timeout value to please some
applications that don't split off the bulk of their calculations as
background jobs.

Doing this of cause, means that connections can get stuck for a longer
time. In particular, we're frequently seeing lots of connections stuck in
the "reading" state (i.e. TCP connection made but no HTTP request sent).

Skimming though the list's archives, I've noticed several other people
have had the issue of "lots of connections in ..Reading.. state". I've
encountered some "vague" discussions about the possibility of this being
caused by either firewall problems or the use of mod_ssl, but haven't yet
found a message describing the exact problem, its cause or workarounds.

So I'm currently left with the following questions:

1. These "..Reading.." connections occur when connecting to the HTTP port,
but not sending an HTTP request. Can they occur when the web server is
waiting for backend data (WebSphere, JBoss) or will the connection be
shown in "W - Sending reply" in the Apache server status?

2. Are there obvious or well-known config mistakes to check when using
mod_ssl, mod_jk and Websphere HTTP plugin that would result in an
increased number of connections being stuck in "..Reading.." state?

3. I haven't figured out a reliable way of identifying the "..Reading.."
connections: all sockets show up in the server status page and in netstat
as being owned by the same process ID (I'm using worker MPM), but the
server status page only displays info relevant to the last or current HTTP
request being processed, so it seems that the client IP displayed next to
"..Reading.." connections can't be used to ID them...

4. At least with Apache 2.2, I believe it is possible to not pass a socket
to the Apache process unless data is actually present using the
AcceptFilter directive, which would not pass "connected but not sending
anything" connections to Apache.
Is there a workaround to have the same feature on Apache 2.0 (as in:
without upgrading to RHEL5 using apache 2.2) ?

Thanks (for reading this far ;-)!
Pieter








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