forked from pool/mariadb
9301fefeac
Copy from server:database/mariadb based on submit request 39217 from user -miska- OBS-URL: https://build.opensuse.org/request/show/39217 OBS-URL: https://build.opensuse.org/package/show/openSUSE:Factory/mariadb?expand=0&rev=1
103 lines
3.3 KiB
Plaintext
103 lines
3.3 KiB
Plaintext
Debugging mysqld crashes
|
|
========================
|
|
Author: Michal Marek <mmarek@suse.cz>
|
|
Last modified: 2006-07-31
|
|
|
|
Contents
|
|
--------
|
|
1) Query log
|
|
2) Coredumps and Backtraces
|
|
3) Trace files
|
|
|
|
In case your MySQL server crashes, here are some hints on what to
|
|
include in a bugreport at https://bugzilla.novell.com/ . Please report
|
|
there only bugs in the MySQL packages packaged by Novell/SUSE, bugs in
|
|
binaries / source provided by MySQL AB should be reported at
|
|
http://bugs.mysql.com/ .
|
|
|
|
1) Query log
|
|
------------
|
|
Note: Skip this chapter if you already have an exact query that
|
|
crashes the server
|
|
|
|
To find out which query possibly crashed the server, add the following
|
|
line to your /etc/my.cnf into section [mysqld]:
|
|
|
|
log=/var/lib/mysql/mysqld-query.log
|
|
|
|
Mysqld then will, at some performance cost, log all queries into this
|
|
file. After a server crash, you can examine the queries from the time it
|
|
crashed and try to reproduce the crash with single queries (this might
|
|
not allways work, eg. if the crash is caused by some race condition).
|
|
|
|
Note that this log file may become extremly large, so if you decide to
|
|
attach it whole to the bugzilla, don't forget to
|
|
|
|
bzip2 -k /var/lib/mysql/mysqld-query.log
|
|
|
|
and attach the bzipped file instead.
|
|
|
|
2) Coredumps and Backtraces
|
|
---------------------------
|
|
Another valuable information for the developers is the backtrace. The
|
|
easies way to get one is to let mysqld produce a coredump. Add the
|
|
following line to your /etc/my.cnf into section [mysqld]:
|
|
|
|
core-file
|
|
|
|
Note: this unfortunatelly doesn't work in SUSE Linux 10.1 and older.
|
|
On these systems, you need to run safe_mysqld directly under user
|
|
mysql:
|
|
|
|
su - mysql
|
|
mysqld_safe --socket=/var/lib/mysql/mysql.sock \
|
|
--datadir=/var/lib/mysql --core-file &
|
|
|
|
The core file will be written to the /var/lib/mysql/ directory. I
|
|
suggest setting the kernel variable kernel.core_uses_pid to 1
|
|
|
|
sysctl -w kernel.core_uses_pid=1
|
|
|
|
so that the coredumps don't overwrite each other if you experience
|
|
multiple crashes.
|
|
|
|
After you got the core file, install the gdb and mysql-debuginfo
|
|
packages and run
|
|
|
|
gdb /usr/sbin/mysqld /var/lib/mysql/core
|
|
(gdb) bt
|
|
|
|
Replace mysqld with the mysqld version you used (mysqld, mysqld-max or
|
|
mysqld-debug) and core with the actual name of the coredump.
|
|
|
|
3) Trace files
|
|
--------------
|
|
You'll need the mysqld-debug binary from the mysql-debug package to get
|
|
a trace file. Install the mysqld-debug package and the start mysqld
|
|
using following command:
|
|
|
|
$ MYSQLD_DEBUG=yes rcmysql start
|
|
|
|
Note: The init script doesn't automatically pick up the mysqld-debug
|
|
binary (as it does with mysqld-max), because it is expected to be used
|
|
just temporarily to help solving a particular problem.
|
|
|
|
The init script will then start mysqld-debug and add the --core-file,
|
|
--log and --debug options for you. The query log will be stored in
|
|
|
|
/var/lib/mysql/myqld-query.log
|
|
|
|
and the trace file in
|
|
|
|
/var/lib/mysql/mysqld.trace
|
|
|
|
If you don't like the options set by the init script, just put your own
|
|
into /etc/my.cnf and the init script will honor it. For information
|
|
about the --debug option, see "The DBUG Package":
|
|
http://dev.mysql.com/doc/refman/5.0/en/the-dbug-package.html .
|
|
|
|
The trace file will contain various debug information and function
|
|
calls/returns and will become _extremly_ huge after a while, so don't
|
|
attach it to bugzilla unless requested.
|
|
|