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Re: TCP Transactions
- From: Matt Jerdonek <maj1224 at yahoo dot com>
- To: Andrew Lunn <andrew at lunn dot ch>
- Cc: Discussion eCos <ecos-discuss at sources dot redhat dot com>
- Date: Tue, 21 Oct 2003 08:42:44 -0700 (PDT)
- Subject: Re: [ECOS] TCP Transactions
--- Andrew Lunn <andrew@lunn.ch> wrote:
> On Mon, Oct 20, 2003 at 04:27:11PM -0700, Matt
> Jerdonek wrote:
> > Hello again,
> >
> > I'm developing an application that sends small
> > transactions via TCP. The basic flow is 1) Bring
> up
> > the connection 2) Send request 3) Get response 4)
> > Bring down the connection. Simple enough ...
> >
> > But, when running any volume of transactions, all
> my
> > socket file descriptors get stuck in TIME_WAIT
> state.
> > When this occurs, my application is effectively
> > disabled until a file descriptor times out.
>
> Is this the client or the server end that has the
> problem?
>
> Are you doing a setsocketopt() for SO_REUSEADDR?
>
>
> Andrew
>
Andrew,
Thanks for the reply. My code is the client end of
the connection. Initially, my code was a call only to
socket() and a call to connect(). I changed it to a
call to socket(), setsockopt(REUSEADDR),
setsockopt(REUSEPORT), bind(), and connect(). In both
cases, it failed. Please look at the following code
from bsd_tcpip/ver/src/sys/netinet/tcp_usrreq.c
-------------------------------------
/*
* Cannot simply call in_pcbconnect, because there
* might be an
* earlier incarnation of this same connection still
in
* TIME_WAIT state, creating an ADDRINUSE error.
*/
oinp = in_pcblookup_hash(...);
if (oinp) {
if (...RFC1644 check...)
otp = tcp_close(otp);
else
return EADDRINUSE;
}
-----------------------------------
I think I have to find a method to shorten the
TIME_WAIT state. The TIME_WAIT state is defined as 2
* MSL (or 60 seconds). If I make the MSL
configurable, I can shorten the TIME_WAIT. Is this
reasonable?
Thanks,
-- Matt
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