Apache half-open socket behaviour

[daniel.goulder@xxxxxxxxx]

Hi apache-users

Platform: Solaris 10, Apache 2.2.11
compiled with Sun Studio 12, mod_jk 1.2.28

I have been having issues while using
Apache with mod_jk (although I am not certain that mod_jk has anything
to do with this)

I have noticed that I am getting a significant
number of connections in server-status that are getting stuck in the W
(sending reply) state.

Packet captures reveal that the client
side is using keep-alives, and is sending several requests, the last of
which is followed shortly afterwards (~250ms) by a FIN.  This would
result in a half-closed connection which as I understand it will stay in
this state until the application closes it, which will result in a FIN
going back to the client.

It appears that httpd has already started
to send data on the socket and then the TCP stack takes over to repeatedly
try to deliver the reply.  No further responses come from the client
and I have a packet capture to show that these connections are staying
in this state for longer than the configured TimeOut value.

On occasion we are finding that all
the children will get into this state and the only remedy is to forcibly
shut down and restart the server.

It appears that from the TCP spec the
client is not obliged to send a reply to the repeated retransmissions,
so surely Apache should obey its TimeOut directive here and let go of the
connection?  Or should I be waiting for the OS to time out the half-closed
connection and kill it?

Thanks

Danny

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