Date: Thu, 10 Sep 1998 12:35:17 +0100 From: james.g.mansion@hsbcgroup.com To: freebsd-current@FreeBSD.ORG Subject: Re: Thread Problems Message-ID: <8025667B.003F044A.00@hbmdtesmtp1.tex.hsbcmidland.com>
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The latest edition of Stevens Network Programming has a discussion on this
point.
The accept should not be done in blocking mode, for exactly the reason
suggested below.
See; UNIX Network Programming 2ed, , W Richard Stevens, Prentice Hall
International, ISBN 0-13-490012-X
The discussion in S15.6,'Nonblocking accept', is pertinent.
James
Daniel Eischen <eischen@vigrid.com> on 10/09/98 11:40:39
To: eischen@vigrid.com, tlambert@primenet.com
cc: freebsd-current@FreeBSD.ORG, info@highwind.com (bcc: James G
MANSION/HBMD/HSBCMERIDIAN)
Subject: Re: Thread Problems
> > I tried to repeat the reported problem, but couldn't. I had
> > one thread listening for client connections, a worker thread
> > (printing a message once a second), and main. The thread
> > listening for client connections would create a thread to
> > handle the connection and go back to accepting more connections.
> > I couldn't make it fail - the worker thread was always spewing
> > out messages once a second. I even tried using fork to
> > process each client request that came in - that worked also.
>
> We really need to get more information.
>
> Effectively, we have the select coming true before the accept call,
> followed by the accept call blocking, even though the select was
> true.
>
> In theory, this can't happen, even with a blocking fd.
Actually, I think this can happen. We were able to reproduce
this (under HP-UX, didn't try FreeBSD) but I forget the exact
circumstances. I think it had something to do when the remote
client attempted to make a connection but closed the socket
before the connection was complete. I'll have to see if I
can find it in my notes - it was 3 or 4 years ago...
> This has got to be a code specific problem. Perhaps they made the
> mistake of the LDAP implementors about number of descriptors, or
> the meaning of "preemptive", and are engaged in a buzz-loop. 8-(.
>
> I just assumed that the person was running -current, and was seeing
> what he thought he was seeing; on the other hand...
I think he was running current - don't know how recent it was
though.
> It would be interesting to know what *exact* version of FreeBSD he
> was running, as well.
>
> Also, if this is a Linux program running under emulation, it should
> not be expected to work...
No, I remember it being code they were porting to FreeBSD.
Dan Eischen
eischen@vigrid.com
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