Bind 8.2.2-REL eating CPU time in tight loop (HP-UX 10.20)

Lutz Jaenicke Lutz.Jaenicke at aet.TU-Cottbus.DE
Thu Nov 4 11:55:32 UTC 1999

On Thu, Nov 04, 1999 at 10:22:29PM +1100, Mark_Andrews at wrote:
> > Just a (stupid?) idea, but why is select dealing with descriptor 26 while
> > later accept is used on descriptor 25??
> 	No, it is saying check the first 26 file descriptors 0..25
> 	for activity.  It finds activity on 2 file descriptors 24
> 	and 25.  24 is a udp socket, 25 is a tcp socket listening
> 	for connections.
Uh, yes, I should have checked select() more carefully. Last time at
dealt with select() was with regard to vgetty on HP-UX and memory seems
to fade...

> 	What is interesting about this is the recvfrom is return
> 	0 to the first call and accept is returning EAGAIN.  Select
> 	has just returned 2 so neither of these conditions should
> 	be occuring normally.
> 	The recvfrom could be due to zero length udp packets and
> 	the EAGAIN could be due to TCP sessions that are being
> 	reset.  I suspect that you are under attack which named is
> 	successfully repelling.  A packet trace may show some pattern.
Hmm, I just had called ethereal and couldn't find anything in this
Also, I would have to look for an idea to "count" the calls to select,
but as it seems, named takes 100% computer time if it can get it,
so it doesn't seem to stay in select() for any amount of time, it
just returns and loops.
This behaviour reminds me of vgetty at that time, but this was 100%
reproducable behaviour.

Ever tried to shut down your X before closing Netscape 4.x cleanly?
It also suddenly starts to eat up CPU time, so maybe there is indeed
something going on around closing TCP connections...
At least as of now, I know a lot about the internals of Postfix, OpenSSL
and some other things, but I never had a look into the bind internals...

Best regards,
Lutz Jaenicke                             Lutz.Jaenicke at aet.TU-Cottbus.DE
BTU Cottbus               http://www.aet.TU-Cottbus.DE/personen/jaenicke/
Lehrstuhl Allgemeine Elektrotechnik                  Tel. +49 355 69-4129
Universitaetsplatz 3-4, D-03044 Cottbus              Fax. +49 355 69-4153

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