Mysql – bind9 dlz/thesql at ubuntu segfault libthesqlclient.so

binddomain-name-systemMySQLsegmentation-fault

I have a big problem.
I installed the bind9 nameserver to three different computer.
two Ubuntu 10.04.4 LTS, and one Ubuntu 11.10

I compiled it 9.7.0, 9.7.3, 9.9.0 with this method:

./configure --prefix=/usr --sysconfdir=/etc/bind --localstatedir=/var \
--mandir=/usr/share/man --infodir=/usr/share/info \
--enable-threads --enable-largefile --with-libtool --enable-shared --enable-static \
--with-openssl=/usr --with-gssapi=/usr --with-gnu-ld \
--with-dlz-mysql=yes --with-dlz-bdb=no \
--with-dlz-filesystem=yes --with-geoip=/usr

make

make install

After the set up for dlz/mysql, the BIND server is working perfetctly until 5-30 minute long. Ahter i got segfault.

I resolve temporaly the problem with a simple process watchdog, and if the named is stopped, the watchdog is restart it, but this is not a good idea in long therm.

My log output is:

messages:

Apr 13 19:33:51 dnsvm kernel: [    8.088696] eth0: link up
Apr 13 19:33:58 WATCHDOG: named not running. Restarting
Apr 13 19:35:08 dnsvm kernel: [   87.082572] named[1027]: segfault at 88 ip b71c4291 sp b5adfe30 error 4 in libmysqlclient.so.16.0.0[b714e000+1aa000]
Apr 13 19:35:08 WATCHDOG: named not running. Restarting
Apr 13 19:35:08 dnsvm kernel: [   87.457510] named[1423]: segfault at 68 ip b71d6122 sp b52f0a40 error 4 in libmysqlclient.so.16.0.0[b7160000+1aa000]
Apr 13 19:35:09 WATCHDOG: named not running. Restarting
Apr 13 19:41:56 dnsvm kernel: [  494.838206] named[1448]: segfault at 88 ip b731c291 sp b5436e30 error 4 in libmysqlclient.so.16.0.0[b72a6000+1aa000]
Apr 13 19:41:57 WATCHDOG: named not running. Restarting
Apr 13 19:57:26 dnsvm kernel: [ 1424.023409] named[2976]: segfault at 88 ip b72d1291 sp b6beee30 error 4 in libmysqlclient.so.16.0.0[b725b000+1aa000]
Apr 13 19:57:26 WATCHDOG: named not running. Restarting
Apr 13 20:11:56 dnsvm kernel: [ 2294.324663] named[6441]: segfault at 88 ip b7357291 sp b6473e30 error 4 in libmysqlclient.so.16.0.0[b72e1000+1aa000]
Apr 13 20:11:57 WATCHDOG: named not running. Restarting

syslog:
http://pastebin.com/hjUyt8gN

the first server is a native, normal x64 server (u1004lts), the second is virtualised server (u11.10) the third is also virtualised (10.04lts) This servers is only for dns providing with mysql server db. But the problem is be with all server, and all bind version.

named.conf:
http://pastebin.com/zwm1yP7V

Can anybody help me, or any good idea?

Best Answer

The problem: (from http://bind-dlz.sourceforge.net/mysql_driver.html)

The MySQL driver has one additional limitation. MySQL uses thread local storage in its C api. Thus MySQL requires that each thread of an application execute a MySQL "thread initialization" to setup the thread local storage. This is impossible to do safely while staying within the DLZ driver API. This is a limitation caused by MySQL, and not the DLZ API. Because of this BIND MUST only run with a single thread when using the MySQL driver. To ensure BIND runs with a single thread pass "-n 1" on the command line when starting BIND (named). This should not be a limitation on most UN*X systems as BIND is normally compiled single threaded (there are some exceptions). Even if BIND is compiled to support threads passing "-n 1" on the command line will cause it to use a single thread. Also, if the MySQL driver is compiled into BIND but NOT USED then "-n 1" is not required. The "-n 1" command line parameters are only required when the MySQL driver is USED.

RESOLVE:

nano /etc/defaults/bind9

and change this line:

# startup options for the server
OPTIONS="-u bind"

to:

# startup options for the server
OPTIONS="-u bind -n 1"

restart the DNS server.

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what version of redhat are you running ? you can find the rpms on ftp.redhat.com

Mysql – Too many MySQL processes

mysql     9804  0.0  0.6 58556 22960 pts/0   S    12:43   0:00  \_ /usr/sbin/mysqld --basedir=/ --datadir=/var/lib/mysql --user=mysql --pid-file=/var/lib/mysql/myhostname.pid --skip-external-locking --port=3306 --socket=/var/lib/mysql/mysql.sock
mysql     9807  0.0  0.6 58556 22960 pts/0   S    12:43   0:00      \_ /usr/sbin/mysqld --basedir=/ --datadir=/var/lib/mysql --user=mysql --pid-file=/var/lib/mysql/myhostname.pid --skip-external-locking --port=3306 --socket=/var/lib/mysql/mysql.sock
mysql     9808  0.0  0.6 58556 22960 pts/0   S    12:43   0:00          \_ /usr/sbin/mysqld --basedir=/ --datadir=/var/lib/mysql --user=mysql --pid-file=/var/lib/mysql/myhostname.pid --skip-external-locking --port=3306 --socket=/var/lib/mysql/mysql.sock
mysql     9809  0.0  0.6 58556 22960 pts/0   S    12:43   0:00          \_ /usr/sbin/mysqld --basedir=/ --datadir=/var/lib/mysql --user=mysql --pid-file=/var/lib/mysql/myhostname.pid --skip-external-locking --port=3306 --socket=/var/lib/mysql/mysql.sock
mysql     9810  0.0  0.6 58556 22960 pts/0   S    12:43   0:00          \_ /usr/sbin/mysqld --basedir=/ --datadir=/var/lib/mysql --user=mysql --pid-file=/var/lib/mysql/myhostname.pid --skip-external-locking --port=3306 --socket=/var/lib/mysql/mysql.sock
[ ... repeated output truncated ... ]

They're not using 13 * 50mb of ram -- They're probably using something like 70mb total. Remember that that linux will share unmodified memory pages between processes, so if your server is freshly started most of that memory would all be shared. In fact, since mysql is threaded there will only probably be even less memory allocated per thread. If you're concerned about the memory usage of each mysql process, look at /etc/mysql/my.cnf, and look at the variables in the mysqld section:

key_buffers
thread_stack
thread_cache_size
max_connections
query_cache_limit
query_cache_size

Be warned though, that those are very powerful variables to tune, and you can easily kill your mysql performance setting them too low, or waste memory that could be used elsewhere by setting them too high.

One easy starting point to figure out the best way to tune your mysql instance is to run your app for a little bit, then run the mysqltune script, which will analyze your performance counters, then produce a recommendation on what you should change in your server config.

Best Answer

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