[cups.bugs] [HIGH] STR #1757: CUPs crashes with Unable to open "/dev/null" - Too many open files message

[Marcos Martins da Silva]

[STR New]

We have a Fedora Core 5 fully updated and running on a IBM Server
(Netfinity 5500 PII 350 MHz 512MB RAM 40 GB RAID 5 array). The server is a
File and Print server only. It's running Samba (3.0.22) and CUPS (1.2.1)
all stock RPM packages from Fedora Core. CUPS runs smoothly most of time
and we have noted no performance bottlenecks (mean CPU load of 15%). It
manages a total of 13 printers. We note the problem when users complain
they can not print, because there is no other strange symptom on server.
In all events we find this message on /var/log/cups/error_log:
 Unable to open "/dev/null" - Too many open files.
After that, CUPS crash and in order to fix the problem we have just to
restart the service (typing "service cups restart" on server's command
prompt). It shows a failed message on stopping, as expected, and an OK
message on starting. After that, all works fine until the next crash. The
crashes happens day or night, including weekends (we are a Hospital). We
tried to investigate running lsof and we find more than 900 open files on
/dev/null. We use ulimit -n to increase from 1024 (default limit per user)
to 4096, 8192 and now 16384 for root user. We are running a script on a
hourly base to count open files and restart cups in case we reach 6000
open files mark. The problem is less frequent now but still happens. I am
attaching /etc/cups/cupsd.conf, /var/log/cups/error_log, a "lsof | grep
/dev/null" file (debug1) and a "lsof | awk  '{printf("%s\n",$1)}' | sort |
uniq -c | sort -n" (debug2).   We hope you can help us. Thanks in advance.

Link: http://www.cups.org/str.php?L1757
Version: 1.2.1
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