Edit report at https://bugs.php.net/bug.php?id=60078&edit=1
ID: 60078
User updated by: odou...@php.net
Reported by: odou...@php.net
Summary: SIGSEGV in xhprof.c
Status: Open
Type: Bug
Package: xhprof
Operating System: -
PHP Version: Irrelevant
Block user comment: N
Private report: N
New Comment:
System is Linux 64 x64 (kernel 2.6.36)
Bi CPU Intel(R) Xeon(R) CPU L5630 @ 2.13GHz
I found this bug on a particular machine where some CPUs are deactivated on
purpose
(sorry, this is a major information but I only detected it now).
Command used to deactivate a thread: echo 0 >
/sys/devices/system/cpu/cpu1/online
function bind_to_cpu failed for cpu 1, and now I can see why.
Do you have any idea how to handle this on xhprof ? Maybe not resetting the
whole
hp_globals.cpu_frequencies array if bind_ failed ?
Previous Comments:
------------------------------------------------------------------------
[2011-10-19 17:39:26] scott...@php.net
Any more information about the OS or version of PHP? I have this working fine
on
OS X with PHP 5.3 and PHP 5.4.
------------------------------------------------------------------------
[2011-10-18 13:22:27] odou...@php.net
More debugging :
it seems bug is happening in get_cpu_frequency() that returned 0 on line 1335
so
array hp_globals.cpu_frequencies is
wiped out by function clear_frequencies();
Just before, we have an error ("setaffinity: Invalid argument") thrown by line
1228, so my guess is that function
bind_to_cpu() failed, and at the end program is segfaulting because this has an
impact on an array.
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[2011-10-17 16:51:21] odou...@php.net
Description:
------------
I'll try to be as precise as possible :
This happens in a special case that can be reproduced 100%, but I cannot
provide
a test
script (it is using 20MB of closed customer code).
This happens only whith xhprof_enable(). No problem is encountered when the
module is just
loaded with no call to xhprof_enable()
In latest clone from git (commit a6bae51236 for file xhprof.c)
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff3575f49 in hp_mode_shared_endfn_cb (top=0xef0210, symbol=<value
optimized out>)
at /usr/src/xhprof/extension/xhprof.c:1553
bt
#0 hp_mode_shared_endfn_cb (top=0xef0210, symbol=<value optimized out>) at
/usr/src/xhprof/extension/xhprof.c:1553
#1 0x00007ffff357609e in hp_mode_hier_endfn_cb (entries=<value optimized out>)
at
/usr/src/xhprof/extension/xhprof.c:1573
#2 0x00007ffff3576e66 in hp_compile_file (file_handle=<value optimized out>,
type=8) at
/usr/src/xhprof/extension/xhprof.c:1721
#3 0x00000000007218a4 in ?? ()
#4 0x000000000071f294 in execute ()
#5 0x00000000006faf7b in zend_execute_scripts ()
#6 0x00000000006b573a in php_execute_script ()
#7 0x0000000000772287 in main ()
Ok so problem is in the function "hp_mode_shared_endfn_cb"
Let's try to see what is the value of each variable here :
print /f hp_globals.cpu_frequencies[hp_globals.cur_cpu_id]
Cannot access memory at address 0x0
ok so problem is in this expression.
print hp_globals.cpu_frequencies
$8 = (double *) 0x0
(gdb) print /f hp_globals.cur_cpu_id
$9 = 0
Ok so I can see that hp_globals.cpu_frequencies equals NULL (right ?), and we
attempt to
access it as an array.
I read the source code quickly, and I can see that this array should be filled
at some
point. Seems it is not.
I made a dirty patch just to avoid the SIGSEGV, but all my timings in xhprof
reports are
inaccurate now.
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Edit this bug report at https://bugs.php.net/bug.php?id=60078&edit=1
