Date: Mon, 8 Jan 2001 21:44:49 -0500 From: "Bosko Milekic" <bmilekic@technokratis.com> To: <owensmk@earthlink.net>, <hackers@FreeBSD.ORG> Subject: Re: FIN_WAIT_2 / TIME_WAIT Confusion Message-ID: <003b01c079e6$2303bb60$25cbca18@jehovah> References: <01010820025300.00397@mike>
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Hi Michael,
What version of FreeBSD are you running? If it's not too much trouble,
can you please provide the code you're using to simulate the problem? Are the
TIME_WAIT state connections eventually timing out/disappearing?
Michael wrote:
> If this is not proper place to ask this, let me know and I'll go elsewhere
as
> it is a TCP question. . . but I specifically use (and prefer) FreeBSD.
>
> I wrote a simple little I/O multiplexing thing that can act as a client or
> server as a personal project in network programming. Everything seems fine,
> except that when I use the client to make multiple connections to a web
> server.
>
> Even though I don't primarly use it for this, the following behvior has me
> curious.
>
> I will run my client about 2 or three times, each time it makes 5
> connections, pulling back the main page. Then the weird behavior starts:
>
> 1. I will get all data back from all connections except for one, perhaps
> two, which then sit in a FIN_WAIT_2 or sometimes TIME_WAIT state.
>
> 2. When I run netstat -a, it indicates that there is data in the read queue
> for these clients, but select() always returns 0 ready file descriptors.
>
> That's what puzzles me. There is data there to be gotten, but I am not
> getting it. When I look at the data that comes back in tcpflow, it doesn't
> look like the whole document has made it back either.
>
> A couple of runs might work perfectly, then once or twice will be weird.
And
> it seems to multiplex more connections more reliably than fewer (the weird
> behavior seems inversely proportional to the number connections---to a
point
> of course. The client runs reliably more times with 50 connections than
with
> 5).
>
>
> Three notes:
>
> 1. It seems to happen more if I access machines on my LAN than over the
> Internet.
>
> 2. I do make sure and shutdown the write side of the socket after I send
the
> HTTP request so as to avoid keeping the web server in FIN_WAIT_2.
>
> 3. I am sure about having the maxfd + 1 in select() correct, so that's not
> the problem.
>
> Does anyone have any ideas as to what's going on?
>
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