httpd-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Mark Montague <m...@catseye.org>
Subject Re: [users@httpd]Apache2 and double free or corruption
Date Thu, 15 Sep 2011 04:17:36 GMT
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


---------------------------------------------------------------------
The official User-To-User support forum of the Apache HTTP Server Project.
See <URL:http://httpd.apache.org/userslist.html> for more info.
To unsubscribe, e-mail: users-unsubscribe@httpd.apache.org
   "   from the digest: users-digest-unsubscribe@httpd.apache.org
For additional commands, e-mail: users-help@httpd.apache.org


Mime
View raw message