Hi,
I've got a apache core file due to a crash from a 3rdparty module. But
the first thread shown in "thread apply all bt full" is this:
Core trace extracted from /usr/local/httpd/service/httpd/core.20252
follows:
Using host libthread_db library "/lib/i686/nosegneg/libthread_db.so.1".
warning: Can't read pathname for load map: Input/output error.
warning: Lowest section in /usr/lib/libicudata.so.36 is .gnu.hash at
000000b4
Core was generated by `httpd.worker -DNO_DETACH -f
/usr/local/httpd/config/httpd.conf'.
Program terminated with signal 11, Segmentation fault.
#0 0xbfffe402 in __kernel_vsyscall ()
#0 0xbfffe402 in __kernel_vsyscall ()
#1 0xb7d45ebb in read () from /lib/i686/nosegneg/libpthread.so.0
#2 0x8003c6c0 in ap_mpm_pod_check (pod=0x8011bcb0)
at /usr/include/bits/unistd.h:35
#3 0x8003a017 in child_main (child_num_arg=<value optimized out>)
at /usr/src/debug/httpd-2.2.4/server/mpm/worker/worker.c:1258
#4 0x8003a1c0 in make_child (s=0x8005f468, slot=0)
at /usr/src/debug/httpd-2.2.4/server/mpm/worker/worker.c:1341
#5 0x8003a2ad in startup_children (number_to_start=1)
at /usr/src/debug/httpd-2.2.4/server/mpm/worker/worker.c:1375
#6 0x8003b022 in ap_mpm_run (_pconf=0x8005d5c8, plog=0x8008b680,
s=0x8005f468)
at /usr/src/debug/httpd-2.2.4/server/mpm/worker/worker.c:1725
#7 0x80010958 in main (argc=-2147109312, argv=0x0)
at /usr/src/debug/httpd-2.2.4/server/main.c:717
eax 0xfffffe00 -512
ecx 0xbfee4c53 -1074901933
edx 0x1 1
ebx 0x5 5
esp 0xbfee4c20 0xbfee4c20
ebp 0xbfee4c58 0xbfee4c58
esi 0x80130ad8 -2146235688
edi 0x0 0
eip 0xbfffe402 0xbfffe402 <__kernel_vsyscall+2>
eflags 0x200293 [ CF AF SF IF ID ]
cs 0x73 115
ss 0x7b 123
ds 0x7b 123
es 0x7b 123
fs 0x0 0
gs 0x33 51
The actual thread that caused the crash shows somewhere below after
many other threads. It looks like this.
Thread 39 (process 13697):
#0 0xbfffe402 in __kernel_vsyscall ()
No symbol table info available.
#1 0xb7bd35f6 in kill () from /lib/i686/nosegneg/libc.so.6
_nl_category_name_idxs = {11 '\v', 32 ' ', 43 '+', 0 '\0', 20
'\024',
51 '3', 0 '\0', 63 '?', 72 'H', 80 'P', 91 '[', 104 'h', 119 'w'}
_nl_msg_cat_cntr = 1
#2 0x8002e91e in sig_coredump (sig=11)
at /usr/src/debug/httpd-2.2.4/server/mpm_common.c:1188
No locals.
#3 <signal handler called>
No symbol table info available.
#4 0xb71b8e97 in PSSessionMan::terminateStaleSessions (this=0x807eb2d8)
at services.cpp:910
lOs = <incomplete type>
lIR = <value optimized out>
...
...
I know the bug in the 3rdparty code and its fixed. But my question is
why does this thread not show up first in the "thread apply all bt
full" listing. Note that if I run apache attached to gdb and this
crash happens and then I do bt, I see this thread first. (Since gdb
intercepted the sig 11 and apache's sig_coredump handler didn't get
invoked). Is this expected behavior? Can I rely on the understanding
that the thread that has the sig_coredump handler invoked is the
thread that caused the crash?
Thanks,
--
Vinay Y S
