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From "Roy T. Fielding" <field...@kiwi.ICS.UCI.EDU>
Subject Re: [PATCH] lingering_close performance improvement
Date Mon, 10 Feb 1997 14:53:11 GMT
>I seem to recall that there were many(?) cases where if people recompiled
>with NO_LINGCLOSE the FIN_WAIT_2 problem "went away"... Now this may
>have been fixed with the latest rev to l_c(), but maybe not.

No, it just appeared to go away -- I tested both and it made no difference
in terms of the client-holding-connection-open FIN_WAIT_2 problem.
The only thing that reduces that problem is disabling keep-alive,
or adding a FIN_WAIT_2 timeout.

The other FIN_WAIT_2 problem, of mixing timeout and abort and l_c(),
was fixed in 1.2b6 and has not been seen since.

The only concern we have with l_c() right now is the length of the
timeout and the fact that it might block in a read(), both of which
are fixed in my patch which people have failed to vote on.

>(although there still seems to be some disagreement on whether
>l_c() is even needed according to the 1.1 specs) but if not then
>we can't blame it on keepalive clients.

Well, the only disagreement I've seen is the desire to ignore the
problem and hope it goes away on its own.  It won't -- both the TCP
and HTTP/1.1 specs anticipate that it will be a normal occurrence
if the server wishes to ensure reliable delivery of data after a server
close in an environment where the client might send additional data.

....Roy

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