I'm facing the same problem here, but I found much lower settings on our machine (a VPS running Ubuntu 12.04):

# the hard limit of open files
www-data@215247:~$ ulimit -Hn
4096
# the soft limit of open files
www-data@215247:~$ ulimit -Sn
1024
# maximum number of file descriptors enforced on a kernel level
# for more info see: http://serverfault.com/q/122679/88043
root@215247:~# cat /proc/sys/fs/file-max
262144

So I would hope that setting the ulimit values for max open files per user to 262144 (H) and 131072 (S) will help.

But then again, Howard Chen mentioned, that he's facing this problem despite such high values on his system.

Any suggestions?

Oliver
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