why would I get a segmentation fault on one system but not the other?

[David Benfell]

On Sun, Feb 22, 2015 at 03:43:03PM -0600, Valeri Galtsev wrote:
> 
> No, I'm too inclined now to think it is not hardware. Swapping the drives
> between two boxes will confirm that that is not the hardwre case
> definitely... At this point I would think of likely memory leak somewhere.
> One of the things would be just run that thing in debugger. You will know
> exact place where it fails, and will see if failure reproduces.

I hope I did this right. It's the first time I've tried working with
the debugger. If I did this right, then ick:

vegan# gdb /usr/local/sbin/php-fpm
GNU gdb 6.1.1 [FreeBSD]
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and
you are
welcome to change it and/or distribute copies of it under certain
conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for
details.
This GDB was configured as "amd64-marcel-freebsd"...(no debugging
symbols found)...
(gdb) break main
Breakpoint 1 at 0x648214
(gdb) run
Starting program: /usr/local/sbin/php-fpm 
(no debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...[New LWP
100184]
(no debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...[New Thread 802806400 (LWP 100184/php-fpm)]
[Switching to Thread 802806400 (LWP 100184/php-fpm)]

Breakpoint 1, 0x0000000000648214 in main ()
(gdb) attach 1458
A program is being debugged already.  Kill it? (y or n) n
Not killed.
(gdb) n
Single stepping until exit from function main, 
which has no line number information.
(no debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
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debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
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debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
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debugging symbols found)...(no debugging symbols found)...(no
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debugging symbols found)...(no debugging symbols found)...(no
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debugging symbols found)...(no debugging symbols found)...(no
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debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
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debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
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debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
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debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
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debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...(no debugging symbols found)...(no
debugging symbols found)...
Program received signal SIGSEGV, Segmentation fault.
0x000000080a9903e8 in hash_lookup () from
/usr/local/lib/libc-client4.so.9

> Before
> that I would do some quick look around. Is it possible that some thing
> calls itself recursively? This will create quickly new processes, the last
> you can spot happening, right? I do realize now the other machine is
> production machine. Can you use recovery from backup of production machine
> to re-create it exactly on failing box? This will cover what swapping the
> drive will do. And in case of success you will have working box. Still, on
> production machines I would use RELEASE (as it was already mentioned).
> Sorry, I didn't follow this thread from beginning; I may be suggesting
> something irrelevant...
> 
> Good luck!
> 
> Valeri
> 
> ++++++++++++++++++++++++++++++++++++++++
> Valeri Galtsev
> Sr System Administrator
> Department of Astronomy and Astrophysics
> Kavli Institute for Cosmological Physics
> University of Chicago
> Phone: 773-702-4247
> ++++++++++++++++++++++++++++++++++++++++

-- 
David Benfell <benfell at parts-unknown.org>
See https://parts-unknown.org/node/2 if you don't understand the
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