Re: a possible bug in expect/tcl: a hypothesis

From: John Zwiebel (jzwiebel_at_cisco.com)
Date: 01/03/05 

Date: Mon, 03 Jan 2005 08:54:46 -0800

Todd J Martin wrote:
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> John Zwiebel wrote:
> | I assume (please correct me) that the kernel has a thread that
> | monitors the CPU usage of all processes. When the CPU is
> | pegged at 100% for x period, that process is killed. Exactly
> | what is happening to my script.
> |
> | I'd like a theory on why it sometimes works. Is it
> | because a different process other than my script is
> | getting killed? -or- has the script somehow received
> | and correctly processed the entire table from the
> | remote-system. (It doesn't look like it)
> |
>
> This could be a setting on the shell. See ulimit -t. You may also want
> to check ulimit -c, just in case it is crashing, but the system does not
> allow a core file to be generated.

Thanks a lot. You stopped me from going down a dead-end.

No corefile, so that points the problem back to my script.

Changing the limits on those items I could change did not
affect the results while running inside of emacs.

FWIW: here is a comparison of the limits. On the Linux
system, the limits allow the script to "power through" meaning
although the problem shows up, the script doesn't quit.

I really would like to be able to change the number of pipes to
see what happens.

                                    default mod results
                                    --------- ---
ulimit -a
core file size (blocks, -c) 0 unlimited [No core

                                                             file]
data seg size (kbytes, -d) 6144 unlimited None
file size (blocks, -f) unlimited --
max locked memory (kbytes, -l) unlimited --
max memory size (kbytes, -m) unlimited --
open files (-n) 256 1024 None
pipe size (512 bytes, -p) 1 8 *Not permitted
stack size (kbytes, -s) 8192 --
cpu time (seconds, -t) unlimited --
max user processes (-u) 100 300* *Not

                                                             permitted
virtual memory (kbytes, -v) 14336 *Not
                                                             permitted
sh-2.05b$

Linux defaults
--------------
sh-2.05a$ ulimit -a
ulimit -a
core file size (blocks, -c) unlimited
data seg size (kbytes, -d) unlimited
file size (blocks, -f) unlimited
max locked memory (kbytes, -l) unlimited
max memory size (kbytes, -m) unlimited
open files (-n) 1024
pipe size (512 bytes, -p) 8
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 7168
virtual memory (kbytes, -v) unlimited

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