| [ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
On most systems you can also start mysqld from gdb to get
more information if mysqld crashes.
With some older gdb versions on Linux you must use run
--one-thread if you want to be able to debug mysqld threads. In
this case you can only have one thread active at a time. We recommend you
to upgrade to gdb 5.1 ASAP as thread debugging works much better with this
version!
When running mysqld under gdb, you should disable the stack trace
with --skip-stack-trace to be able to catch segfaults within gdb.
In MySQL 4.0.14 and above you should use the --gdb option to
mysqld. This will install an interrupt handler for SIGINT (needed
to stop mysqld with ^C to set breakpoints) and disable stack
tracing and core file handling.
It's very hard to debug MySQL under gdb if you do a lot of
new connections the whole time as gdb doesn't free the memory for
old threads. You can avoid this problem by starting mysqld with
-O thread_cache_size= 'max_connections +1'. In most cases just
using -O thread_cache_size=5' will help a lot!
If you want to get a core dump on Linux if mysqld dies with a
SIGSEGV signal, you can start mysqld with the --core-file option.
This core file can be used to make a backtrace that may help you
find out why mysqld died:
shell> gdb mysqld core gdb> backtrace full gdb> exit |
See section A.4.1 What To Do If MySQL Keeps Crashing.
If you are using gdb 4.17.x or above on Linux, you should install a `.gdb' file, with the following information, in your current directory:
set print sevenbit off handle SIGUSR1 nostop noprint handle SIGUSR2 nostop noprint handle SIGWAITING nostop noprint handle SIGLWP nostop noprint handle SIGPIPE nostop handle SIGALRM nostop handle SIGHUP nostop handle SIGTERM nostop noprint |
If you have problems debugging threads with gdb, you should download gdb 5.x and try this instead. The new gdb version has very improved thread handling!
Here is an example how to debug mysqld:
shell> gdb /usr/local/libexec/mysqld gdb> run ... backtrace full # Do this when mysqld crashes |
Include the above output in a mail generated with mysqlbug and
mail this to the general MySQL mailing list.
See section 1.7.1.1 The MySQL Mailing Lists.
If mysqld hangs you can try to use some system tools like
strace or /usr/proc/bin/pstack to examine where
mysqld has hung.
strace /tmp/log libexec/mysqld |
If you are using the Perl DBI interface, you can turn on
debugging information by using the trace method or by
setting the DBI_TRACE environment variable.
| [ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |