On 17 Feb 2006, at 20:50, Jorn Hass wrote:
>
> Hi all...
>
> First of, a huge wave to David L. for a great piece of software...
> Secondly a big wave to the rest on this list...
>
> (For the record, I'm in sunny (Currently) Johannesburg, South
> Africa... [We have been tormented with torrential rains in the last
> month or so...])
>
> I am new to this list, so please bear with me if this has all been
> done and said...
>
> I came across a serious problem with re-entrance on FreeBSD 5.4, and
> found various references to the issue. Basically XMail server would
> keep "freezing" with an error logged to the syslog in the form of:
> Feb 14 20:43:22 mailbox XMail[46411]: Unable to create file
>
> This would mostly happen after a flood of spamming attempts, or
> someone hammering the server with POP requests... (Like 5-7
> requests/second for the next week...)
>
> Restarting XMail nightly worked for the most part, but that was
> treating the symptom, not the problem...
>
> This is after successfully running it on FreeBSD 4.5 for a long
> time...
>
> As this was one of my "pet projects", I didn't have much time sniffing
> and searching for clues, so it took me a while... Hence the nightly
> reboot...
>
> The only reference to the "unable to open file" error, on the
> xmailserver site, only appears in the SMTP Error messages under -19,
> which didn't tell me much...
>
> So I went digging and found a reference to KQUEUE entries not being
> released.
>
> So the direct reference I found, said, remove "-lr_c" from MakeFile,
> and the problem would be resolved... Did that, and had a violent crash
> with coredump... :(
>
> So I checked some more, and there where references to SMP kernels and
> re-entrant issues. This seems to be in effect with any 5.x kernel. I
> then figured out how to do it...
>
> So a quick rundown on check/solution:
> Install lsof for FreeBSD
> run "lsof | grep XMail | grep KQUEUE". If these keep increasing,
> particularly after a POP mailcheck, without decreasing, your system
> suffers from this problem...
>
> Patch the kernel as given at:
> http://www.freebsd.org/cgi/query-pr.cgi?pr=threads/75795
> Rebuild kernel and reboot.
>
> Now it won't have the problem anymore, and I can see the KQUEUEs
> popping in and out on my box...
>
> I have not found a direct thread on this particular problem, and the
> kernel patches are still not in the latest release (5.4rc11), so I
> think there might be more people with this issue, and hopefully this
> bit might help them...
>
> I have rebooted with the new kernel this morning, and hopefully I
> should have peace and quiet overnight... I will report more on this,
> should I notice any more issues...
I've been suffering this problem since move from xmail-1.17 on
FreeBSD 4.10 on a Celeron 2400 box to xmail-1.2x on FreeBSD 5.3 on a
586-133MHz PC. I'd tried same patch last April but not had much luck
as this seemed to introduce other stability problems affecting the
system (possibly resolved in CURRENT). Anyway up to tonight I was
restarting xmail every 14 days or so although not gone much over 40
days without a crash or shutting down for other reasons :-(.
I rebooted to a patched kernel again last night and was going to see
how long I get (I think previous longest uptime with patched kernel
was < 20 days). Ouch, that was up about 8hr 50min, but as I had a
kernel panic during reboot to new kernel I'll give it another go with
fsck from single user first however I'm not optimistic and gained
impression from various lists that stability issues were introduced
with the kqueue_stat code which is why it wasn't present.
It certainly prevents number of open files increasing (with light
load and no patch I'm up to 2000 after a couple of weeks and with
patch it's around 19 total for XMail).
David
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