perhaps i can add more info, after doing more investigation:

a.   "ulimit" is a shell feature, it is not a command line binary.   "man
bash" and "man sh" and u can see ulimit has different feature available for
u.

b.   ulimit control all the resources defined by the processes spawn from
the current shell onwards...ie, once ulimit is change, all child processes
from that shell onwards will change.  but resources limit in another shell,
existing processes etc does not.

c.   ulimit is a userspace feature, the kernel will have all the
corresponding feature of max open files etc...but definitely it is not
unlimited like that of ulimit.

d.   to see ALL the open files u can use "lsof" and "-p" give u control to
point at which process to dig for open files.   it also list all the open
connections (TCP) for u....which is what u want.

e.   generally java applications will open many many files descriptor
concurrently:

http://www.java.net/forum/topic/glassfish/glassfish/too-many-open-files-issue

(above listed 4500, and many others java apps like IBM RSA also have many).

On Sat, Feb 9, 2013 at 1:10 PM, horseriver [off-list ref] wrote:

hi:)

   In one process ,what is the max number of opening file descriptor ?
   Can it be set to infinite ?

   In network programing ,what is the essential for  the maximum of
connections
   dealed per second

thanks!

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-- 
Regards,
Peter Teoh
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