[H-GEN] Apache segfaulting... how to debug
Andrae Muys
andrae.muys at braintree.com.au
Wed Jul 9 22:31:40 EDT 2003
[ Humbug *General* list - semi-serious discussions about Humbug and ]
[ Unix-related topics. Posts from non-subscribed addresses will vanish. ]
Michael Anthon wrote:
> [ Humbug *General* list - semi-serious discussions about Humbug and ]
> [ Unix-related topics. Posts from non-subscribed addresses will vanish. ]
>
> Ok, thanks for the inputs gents. So far I have been able to get an
> strace of a process that is dying
> (http://tamsapp.pwcglobal.com.au/mca/temp/12978.trc) and one that isn't
> (http://tamsapp.pwcglobal.com.au/mca/temp/12977.trc).
>
> These look fairly similar to me apart from the fact that one terminates
> with a SIGSEGV, which I think fits in with my theory that it only
> happens when the child process is terminated by the parent, and then
> only occasionally.
mmm looks nasty. From the strace my first guess would be head
corruption triggering a SEGV while trying to cleanup post child
termination. If there is a libc conflict (as has been suggested
previously) this might explain it.
The critical lines are the last few:
12978 munmap(0x42a09000, 21132) = 0
12978 munmap(0x42951000, 471868) = 0
12978 close(21) = 0
12978 --- SIGSEGV (Segmentation fault) ---
7300 wait4(-1, [WIFSIGNALED(s) && WTERMSIG(s) == SIGSEGV], WNOHANG,
NULL) = 12978
vs.
12977 munmap(0x42a09000, 21132) = 0
12977 munmap(0x42951000, 471868) = 0
12977 close(21) = 0
12977 munmap(0x40012000, 4096) = 0
12977 semget(IPC_PRIVATE, 4096, IPC_CREAT|IPC_NOWAIT|0x80f20a0|0240) =
-1 ENOSYS (Function not implemented)
12977 _exit(0) = ?
7300 <... wait4 resumed> [WIFEXITED(s) && WEXITSTATUS(s) == 0],
WNOHANG, NULL) = 12977
Note the third munmap. I would also look for somesort of allocation
returning address 0x40012000 to see which memory is being cleaned up at
the time (note: This would the memory being corrupted, NOT necessarally
associated with the corrupting code).
Andrae
--
Andrae Muys But can it generate *quantum* Haiku
<andrae.muys at braintree.com.au> error messages, in Latin, where each
Engineer line of the error message is a
Braintree Communications palindrome? -- Mike Vanier on perl
--
* This is list (humbug) general handled by majordomo at lists.humbug.org.au .
* Postings to this list are only accepted from subscribed addresses of
* lists 'general' or 'general-post'. See http://www.humbug.org.au/
More information about the General
mailing list