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Posted to users@httpd.apache.org by ja...@centrum.cz on 2011/09/12 14:06:44 UTC
Re: [users@httpd]Apache2 and double free or corruption
Ho can I solve this error( taken from the Apache2 log)
*** glibc detected *** (wsgi:myweb: double free or corruption (!prev):
0x089e87c0 ***
======= Backtrace: =========
/lib/i686/cmov/libc.so.6[0xb7dba624]
/lib/i686/cmov/libc.so.6(cfree+0x96)[0xb7dbc826]
/usr/lib/libmysqlclient_r.so.15(my_no_flags_free+0x21)[0xb7a07e01]
....
...
...
it continues further
...
..
======= Memory map: ========
08048000-0809d000 r-xp 00000000 08:01 29771425 /usr/sbin/apache2
0809d000-0809f000 rw-p 00054000 08:01 29771425 /usr/sbin/apache2
0809f000-08c2d000 rw-p 0809f000 00:00 0 [heap]
...
...
...
it continues further
...
Thanks for your help
L.
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Re: [users@httpd]Apache2 and double free or corruption
Posted by Mark Montague <ma...@catseye.org>.
On September 12, 2011 8:06 , jana1972@centrum.cz wrote:
> Ho can I solve this error( taken from the Apache2 log)
>
>
> *** glibc detected *** (wsgi:myweb: double free or corruption (!prev):
> 0x089e87c0 ***
> ======= Backtrace: =========
> /lib/i686/cmov/libc.so.6[0xb7dba624]
> /lib/i686/cmov/libc.so.6(cfree+0x96)[0xb7dbc826]
> /usr/lib/libmysqlclient_r.so.15(my_no_flags_free+0x21)[0xb7a07e01]
> ....
> ...
> ...
> it continues further
> ...
> ..
The information you have provided shows that the problem is related to
WSGI or the MySQL client library in some way. Neither one of these are
a part of Apache HTTP Server, so the problem is not likely to be related
to Apache. Instead, my guess is that the problem is related to whatever
scripting language you are using via a third-party module to generate
pages (Python, Ruby, PHP, or something else) and which in turn uses WSGI
and MySQL.
Here is some generic advice for solving the problem:
- See if you can get a complete backtrace. What you have posted omits a
lot of information about where the problem occurred.
- See if you can get a backtrace that includes debugging symbol
information. How to do this will depend on which operating system you
are using; for example, if you are using Fedora like I am, see
https://fedoraproject.org/wiki/StackTraces Additional debugging advice
is available at https://httpd.apache.org/dev/debugging.html
- Check bug reports for the scripting language you are using to see if
the problem you are encountering is a known issue and whether a fix or a
workaround is available.
- Upgrade to the latest versions of your third-party software (scripting
language, database client libraries, WSGI connector). This will make it
easier to get support from the communities that support that software.
- Make sure that the versions of the software you are running are all
compatible with one another. For example, if you are using Python and
MySQL together, make sure that the version of MySQL you are using is
supported by the version of Python you are using.
- Investigate the conditions under which the problem occurs. Try to
narrow it down to specific scripts or operations, if possible.
- If you are not able to solve the problem, try isolating it. Sandbox
the problematic scripts so that they run as child processes instead of
running inside the web server itself; the scripts will still die, but
their death will no longer directly affect the web server processes. A
number of technologies are available for this, including CGI, FastCGI,
and SGI. I see that you are using WSGI; if you have implemented this
using mod_wsgi ( https://code.google.com/p/modwsgi/ ) then use
mod_wsgi's 'daemon' mode to isolate the problematic script(s) from Apache.
Good luck.
--
Mark Montague
mark@catseye.org
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