open files & stack size

Philip Rowlands phr at doc.ic.ac.uk
Thu Dec 5 20:21:01 CST 2002


On Thu, 5 Dec 2002, Jay Christopherson wrote:

>One of our apps (vendor provided, not custom) is pretty flaky and our
>vendor is telling us that we need to set out file descriptor limits
>(open files) and stack size to unlimited. Currently, they are set to
>1024, and 8192, as reported by ulimit -a.

You could watch the stack size and number of file descriptors in
/proc/<pid>. If the app really is hitting these limits, then yes, you
need to increase them.

>This makes me vaguely uneasy, although I cannot articulate why.
>Somewhere in the back of my mind, it is setting off an alarm, but I
>cannot recall the specifics of why this should alarm me.

The kernel has its own global limit on file
descriptors (/proc/sys/fs/file-max), so in theory setting "unlimited"
file descriptors could allow one errant process to cause havoc.

You probably don't need to set unlimited resources; just double the
limits and try again. Watch the process, watch the resource usage and
see if the flakiness disappears. The vendor *could* be trying to
disguise something like a file descriptor leak, which no amount of
resources will fix.


Cheers,

Phil




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