Difference between revisions of "Core file"
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* Wait until the daemon crashes again. | * Wait until the daemon crashes again. | ||
* Inspect the ''core file'' to find the source of the problem. | * Inspect the ''core file'' to find the source of the problem. | ||
| + | |||
| + | == Debugging symbols == | ||
| + | |||
| + | In order to get meaningful information from a ''core file'', the executable must be built with ''debugging symbols''. | ||
| + | |||
| + | === From a package === | ||
| + | |||
| + | The easiest way to obtain ''debugging symbols'' is by installing an appropriate debugging package. If you're using ''Debian'', you can install such a debugging package using: | ||
| + | apt-get install collectd-dbg | ||
| + | |||
| + | Other distributions may provide debugging packages, too. If you know of such a distribution, please add the information here. | ||
| + | |||
| + | === Compiler flags === | ||
| + | |||
| + | If you installed collectd from source or your distribution doesn't provide a debugging package, you can recompile with the appropriate compiler flags. | ||
| + | |||
| + | The exact flags required depend on the compiler used. If you use the C compiler from the ''GNU Compiler Collection'' (GCC), the flag <code>-g</code> enables the inclusion of debugging symbols. While you're at it, disable optimization using <code>-O0</code>. This makes it easier to interpret the output of the debugger. | ||
| + | |||
| + | Pass the flags to the ''configure'' script using: | ||
| + | $ ./configure ''$OTHER_FLAGS'' CFLAGS="-g -O0" | ||
| + | |||
| + | Other compilers may differ. If you know how, please add the information here. | ||
[[Category:Development]] | [[Category:Development]] | ||
Revision as of 10:49, 22 May 2010
A core file or core dump is a dump of the application state, including all memory contents, to the disk for further inspection. If collectd crashes due to a bug, the best way to debug this is via such a file. Using a debugger it is possible where exactly the problem occurred and under which circumstances.
In order to create and use a core file, you need to take the following steps:
- Create an executable with debugging symbols embedded. You can either re-compile with special flags or install a debugging package if one is available.
- Enable creation of core files.
- Wait until the daemon crashes again.
- Inspect the core file to find the source of the problem.
Debugging symbols
In order to get meaningful information from a core file, the executable must be built with debugging symbols.
From a package
The easiest way to obtain debugging symbols is by installing an appropriate debugging package. If you're using Debian, you can install such a debugging package using:
apt-get install collectd-dbg
Other distributions may provide debugging packages, too. If you know of such a distribution, please add the information here.
Compiler flags
If you installed collectd from source or your distribution doesn't provide a debugging package, you can recompile with the appropriate compiler flags.
The exact flags required depend on the compiler used. If you use the C compiler from the GNU Compiler Collection (GCC), the flag -g enables the inclusion of debugging symbols. While you're at it, disable optimization using -O0. This makes it easier to interpret the output of the debugger.
Pass the flags to the configure script using:
$ ./configure $OTHER_FLAGS CFLAGS="-g -O0"
Other compilers may differ. If you know how, please add the information here.
