Date: Tue, 06 Apr 2004 10:14:26 -0600 From: Brandon Erhart <berhart@ErhartGroup.COM> To: freebsd-net@freebsd.org Subject: The Almighty KQueue Message-ID: <6.0.2.0.2.20040406100638.01c6f288@mx1.erhartgroup.com>
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Hi,
I told you all I'd be back for more :) I am not sure if this is the most
appropriate place to post this, but it seems that you all know what the
hell you're talking about, so I figure you can help me out here.
As I said in my previous post about the FIN_WAIT states, I am writing a web
sucker downer (mirror). What I don't believe I mentioned before is that I
am using the KQueue API in FreeBSD 4.9-REL to take care of watching over my
sockets. I seem to be running into a nasty problem, however.
Here's a scenario. I set the outgoing connections to, say, 5000. The
problem is, the amount of connections my program shows as being connected
is roughly 1/2 to sometimes even 1/8th of what is actually connected. I see
what is "actually connected" by doing a netstat. The program would say
750/5000 connections, while a netstat would show 4500 connections in the
ESTABLISHED state.
You may be saying, "it must be a bug in your connection tracking logic". I
honestly don't think that's it. I have only TWO places in my code where I
check if the connection was successful (and therefore increasing the global
connection counter) -- in the callback function for data read() from
KQueue-monitored fds (all of the sockets), and then also in my main loop (I
check for read, write and connect timeouts there, right after my call to
kevent()).
Basically the main loop looks like, in psuedo-code of course:
while (there_is_still_events)
{
if (kevent()) <-- i pull one event from the kqueue
{
execute_the_callback_function;
}
check_for_read()_write()_and_connect()_timeouts;
check_for_"client_descriptors(basically just a structure that holds info
on the kqueue event)"_that_need_to_be_connected_to_the_next_server_and_do_so;
}
It's pretty straight forward. I have no idea why my program would be
reporting a smaller amount. Is it possible that my program is not getting
ALL the information it needs from kevent()? Perhaps the KQueue is becoming
"full"? Is this possible? Should I be pulling more than one event off the
kqueue at a time?
I have been up ALL NIGHT trying to debug this, and cannot figure it out.
Any and all help is appreciated!
Thanks,
Brandon
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