Tracing FDs

[Shanya Jones]

Hi Casper:

  It is one of our application that is giving error.  We want to determine if it the application that is using too many FDs or the system(Solaris 10)or DNS that is using FDs.  We want to find out which process is using how many FDs using dtrace at give point and time - not lsof nor netstat, pfiles not snoop either, using none of the system commands.

Thanks,
  -Shanya

Subject: Re: [dtrace-discuss] Tracing FDs
Date: Thursday, December 30, 2010, 5:43 AM

  (Apology if this is too naive question.)
  Our system is running out of FDs frequently.

What is the exact symptom or error message?
There is no limit on the global number of file descriptors
(assuming
you're using Solaris)
Casper

[Michael Schuster]

Post by Shanya Jones
  It is one of our application that is giving error.  We want to determine if it the application that is using too many FDs or the system(Solaris 10)or DNS that is using FDs.

perhaps you want to show the *exact* error you're getting, and
describe the circumstances in some detail?

As Casper said, there's no system-wide limit on file descriptors, so
if a specific process is running out of fds (that's what I'm assuming
is happening from what I've seen so far), then it's that process
that's exceeding its limit - see "ulimit(1)" man-page.

Post by Shanya Jones
We want to find out which process is using how many FDs using dtrace at give point and time - not lsof nor netstat, pfiles not snoop either, using none of the system commands.

is this an academic exercise. or a real-world problem? if the latter,
use the tool for the problem not the tool of your fancy :-)

again. assuming it's an open() system call that's returning the error
we're discussing here in the abstract, using a probe looking something
like

pid$target:libc:open:return
/arg1 == -1 && errno == 24/
{
ustack();
}

(but check the man pages and do some testing, I didn't check all the details)

will tell you a lot of where the specific error happens, but it may
not help pinpoint the code that's "wasting" the fds, since it's going
to be the one that happens to trip over the limit, nothing more.

HTH
Michael

Post by Shanya Jones
Thanks,
  -Shanya

Subject: Re: [dtrace-discuss] Tracing FDs
Date: Thursday, December 30, 2010, 5:43 AM

  (Apology if this is too naive question.)
  Our system is running out of FDs frequently.

What is the exact symptom or error message?
There is no limit on the global number of file descriptors
(assuming
you're using Solaris)
Casper

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