System-wide ulimit?

[Steven J. Owens]

Hi all,

     I have a tomcat and mysql app that uses a lot of database
connections.  It looks like it's outpacing the default ulimit for open
files, 1024, so I'm upping it to 4096 for both the tomcat and mysql
processes.  Several questions occur:

1) what other resources, other than raw RAM, disk, cpu, should I be
checking?  Is there any way to measure what's actually being usage?

2) what's the "proper" way to set the ulimit on a script that's
executing?  Right now I just have "ulimit -n 4096" line in the script.
Then again, I have no idea if this is actually working, which leads me
to:

3) how would I check to see the ulimit setting (and any other similar
settings) for an existing process?

4) what's the proper way to set the ulimit for open files on a
system-wide basis?  Edit /etc/profile?

5) is there any potential risk to setting the system-wide ulimit to
4096?  Obviously this consumes some resources, but it's not clear to
me whether it's potential to consume resources, or whether the
resources will be allocated as each process starts, and if so, whether
it's significant or not.

-- 
Steven J. Owens
puff at darksleep.com

"I'm going to make broad, sweeping generalizations and strong,
 declarative statements, because otherwise I'll be here all night and
 this document will be four times longer and much less fun to read.
 Take it all with a grain of salt." - http://darksleep.com/notablog