"tcpflags 0x18<PUSH,ACK>; tcp_do_segment" kernel messages

[Eygene Ryabinkin]

Stefan, good day.

Fri, Aug 17, 2007 at 11:04:20AM +0300, Stefan Lambrev wrote:
> Their response is that the mail server timeout.

And how they are detecting the timeout?  They are using alarm(),
just polling for the time with non-blocking read calls, setting the
socket timeout or something else?

> Now the question is why the program things that the server timeouts when it 
> does not :)

May be this is connected to the socket timeout stuff: chances are
good that the PHP program uses apr_socket_timeout_set(), so there
can be issues with SO_SNDTIMEO/SO_RCVTIMEO socket options in the
-CURRENT.  At least Apache (that I have problems with) sets keep-alived
sockets with apr_socket_timeout_set().  I will try to have a look
if this can be true.

Thanks for your information!

Mike, Robert, there are chances that some timeout code behaves
weirdly.  And maybe the magic number 3 (every 3rd keep-alived
connection seems to be dropped due to the timeout, Stefan sees it
too) should be searched in the timeout code.  Maybe you can give
some hints or point to the exact place where the error can occur?

Thank you.
-- 
Eygene