System freeze due to exhaustion of file descriptors?
System freeze due to exhaustion of file descriptors?
- Subject: System freeze due to exhaustion of file descriptors?
- From: Thomas Tempelmann <email@hidden>
- Date: Thu, 2 Apr 2009 09:52:31 +0200
I have a long thread on the darwin-kernel list regarding a recurring
system freeze my 10.4.11 Server system experiences lately. I like to
figure out what is causing it.
Based on the symptoms (mouse, UI, network still works, but any new
process invocation stalls), there were two suggestions of what might
be the cause:
1. process table is full
2. not enough free file descriptors / too many open files
To prepare for the next freeze, I've ssh'd several times into the
server and issued "sudo -s" to become root.
Last night the freeze occured again and I tested some commands out.
The results:
Internal shell commands still work: a blank "exec" as well as "echo
<arg>", "exit", "pwd", "cd <arg>", "times" work.
But invocation of any external command leads to the stall. Even "exec
unknowncommand" stalls.
Finally I tried this one:
servo2:~ root# echo "test" >f
bash: f: Invalid argument
This error makes no sense, does it? I am root, I am in a home dir
which is writable, and yet it doesn't want to perform the redirection.
This suggests the #2 theory from above, doesn't it? I.e, it tries to
open a file for output and gets back an error, then issues a rather
random error message.
Is there really a system-wide (global) limit on available file descs?
How could I test how many are left, or which apps use most of them
(err, that's probabl "lsof")?
Once before a stall, I had run a shell script in a loop which issued
the "ps" command every 15s. This one did not show any oddities before
the freeze, though. I wonder if I should now do the same with a "lsof"
call? Any better suggestions?
--
Thomas Tempelmann, http://www.tempel.org/
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