said by justin:
you might want 100k simultaneous open tcp conversations. It isn't clear to me why this should be so difficult if the majority of the open conversations were idle.
I'm working on a server that has just those requirements. It does appear that there's a 64K per-process open file limit, though I can't find any documentation to that effect. It's not a system-wide limit -- clients can open 64K connections into the server process from the same machine, giving 128K total open files:
$ cat /proc/sys/fs/file-nr
135360 0 296295
A call to getrlimit(RLIMIT_NOFILE) tells me the per-process limit is 250,000 (that's how I've configured it in /etc/security/limits.conf) but I can't seem to actually achieve that many open connections.
Have you found any information that this limit can be increased?