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Article ID: 3653
Last update: 11-08-04
Issue:
How do I read the core files created by Apache on Red Hat Enterprise Linux systems?
Resolution:
If you have an Apache core file dumped from Apache due to a segmentation fault, then it is best to run a basic parse of the core file and if you would like Red Hat Support to review the data then we would need the output of the basic parse, along with the physical core file itself and a listing of installed software on the system. Below are the steps needed to complete this task.
  1. List the files within directory "/var/apache-dump/": 

     
ls -l /var/apache-dump/
-rw-------    1 apache   apache   71188480 Aug 16 13:48 /var/apache-dump/core.1333


  2. Use gdb to read the Apache core file in question. Hit the Enter key until you get to the '(gdb)' prompt and type in "where". Copy and paste (or re-write) the output from the gdb session and send it to Red Hat Support. Type "quit" to exit: 

     
# gdb /usr/sbin/httpd /var/apache-dump/core.902
GNU gdb Red Hat Linux (5.3.90-0.20030710.41.2.1rh)
Copyright 2003 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 "i386-redhat-linux"...(no debugging symbols
found)...Using host libthread_db library "/lib/libthread_db.so.1".
 
Core was generated by `/usr/sbin/httpd -DHAVE_ACCESS 
    -DHAVE_PROXY -DHAVE_AUTH_ANON -DHAVE_ACTIONS -DHA'.
Program terminated with signal 11, Segmentation fault.
Reading symbols from /lib/i686/libpthread.so.0...done.
Loaded symbols for /lib/i686/libpthread.so.0
Reading symbols from /lib/i686/libm.so.6...done.
Loaded symbols for /lib/i686/libm.so.6

...

Loaded symbols for /usr/lib/perl5/site_perl/5.6.1/i386-linux/auto/Unix/Syslog/Syslog.so
Reading symbols from /lib/libnss_nisplus.so.2...done.
Loaded symbols for /lib/libnss_nisplus.so.2
#0  0x4024aeb2 in semop (semid=131073, sops=0x8087870, nsops=1) 
    at ../sysdeps/unix/sysv/linux/semop.c:36
36      ../sysdeps/unix/sysv/linux/semop.c: No such file or directory.
        in ../sysdeps/unix/sysv/linux/semop.c
(gdb) where
#0  0x4024aeb2 in semop (semid=131073, sops=0x8087870, nsops=1) 
    at ../sysdeps/unix/sysv/linux/semop.c:36
#1  0x0805ce37 in accept_mutex_on_sysvsem ()
#2  0x0805fc13 in child_main ()
#3  0x080602a9 in make_child ()
#4  0x0806034d in startup_children ()
#5  0x080609a0 in standalone_main ()
#6  0x080612a3 in main ()
(gdb) quit


  3. We also recommend that you run the command 
    rpm -qa > /var/apache-dump/rpm-listing-`date +%s`
    to create a snapshot of installed RPMs close to the time that the core file was created. This way if Red Hat asks for the Core file itself, we would also need to know the RPM listing that goes with it to be able to perform accurate analysis ourself of the file for further details.


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General Linux > Web/FTP/Networking > Issue <<   5  of  212  >>