Highly Available MySQL/PHP Applications with mysqlnd

Highly Available PHP/MySQL
Applications with mysqlnd
Jervin Real
PHP-UGPH, June 2014

Highly Available Applications
• … how much your application is able to serve its end users
within a time period

• Usually referred to as 99[..]% uptime

• Usually referred to as 99[..]% uptime
• It actually depends on whose perspective

Keep PHP<>MySQL downtime to a minimum

WTF are you saying? I’m a “devloper"!
No no no no no no!

MySQL HA
• MySQL Native Replication (Single Primary)

MySQL HA
• MySQL Native Replication (Multi-Master)

MySQL HA
• MySQL NDB Cluster

MySQL HA
• Galera based

MySQL HA
• Galera based
• Percona XtraDB Cluster
• MariaDB Galera Cluster
• MySQL+Galera

MySQL HA
• Galera based
• MySQL+Galera
• Tungsten Replicator

MySQL HA
• Galera based
• MySQL+Galera
• Tungsten Replicator
• … and many more

• MySQL Master HA
MySQL HA (External Support)

• MySQL Master HA
• Percona Replication Manager (Pacemaker)

• MySQL Master HA
• Haproxy

• MySQL Master HA
• Haproxy
• Load Balancers

• MySQL Master HA
• Haproxy
• Load Balancers
• MySQL Multi Master

HA via Application
• Traditionally complex to implement
• Unnecessary overhead
• No single point of failure

mysqlnd
• MySQL Native Driver

mysqlnd
• Written C (as all extensions should be!)

mysqlnd
• MySQL Client Libraries no more

mysqlnd
• Smaller memory footprint in many cases

mysqlnd
• Performance statistics

mysqlnd
• Compression

mysqlnd
• Compression
• Plugins

mysqlnd Plugins
• mysqlnd_qc - query result cache

mysqlnd Plugins
• mysqlnd_mux - connection multiplexing

mysqlnd Plugins
• mysqlnd_uh - user handler

mysqlnd Plugins
• mysqlnd_memcache - Memcache (MySQL interface)

mysqlnd Plugins
• mysqlnd_memcache - Memcache (MySQL interface)
• mysqlnd_ms - replication and load balancing

mysqlnd_ms Supported Clusters
• All previously mentioned with few limitations

Limitations (Master-Slave)
• Master is a single point of failure
• Need external help for failover
• . . or, shoot the other node in the foot, this is still HA!

Limitations (Master-Master)
• Risky, even if you try segregating writes per master you
can still lose data

db1
db1

db2
db1

db1 + db2
• Not good if sync_binlog = 0 AND/OR innodb_flush_log_at_trx_commit <> 1
• Not really recommended in general, use appropriate technologies
instead

Some More Limitations
• Lazy connections is on by default
• Each request will create its own connections when needed,
persistent connections may be required
• https://bugs.php.net/bug.php?id=67564
• Be careful with multi-statements and read-write splitting,
they are likely to be executed on slave!
SELECT * FROM tbl; DELETE FROM tbl;

• Single Primary - one writable node
• Multiple Primary - all nodes writable

• Master-Slave

• Master-Slave
• Declare 2 clusters

• Master-Slave
• When primary fails, mark it permanently dead and switch
to secondary

• Master-Slave
• When primary fails, mark
it permanently dead and
switch to secondary
{
"primary": {
"master": {
"master_1": {
"host": "127.0.0.1",
"port": 33001
}
},
"slave": {
"slave_0": {
"host": "127.0.0.1",
"port": 33002
}
}
},
"standby": {
"master": {
"master_1": {
"host": "127.0.0.1",
"port": 33002
}
},
"slave": {
}
}
}

• Master-Slave
• When primary fails, mark
it permanently dead and
switch to secondary
• Works better with
master-master!
{
"primary": {
"master": {
"master_1": {
"host": "127.0.0.1",
"port": 33001
}
},
"slave": {
"slave_0": {
"host": "127.0.0.1",
"port": 33002
}
}
},
"standby": {
"master": {
"master_1": {
"host": "127.0.0.1",
"port": 33002
}
},
"slave": {
}
}
}

• Master-Slave Demo
• https://github.com/dotmanila/demo-me/phpugph201407/
• master-slave.ini
• mysqlnd_ms_ms.ini
• master-slave.php

• Multi-Masters (NDB, Galera)
• Declare all nodes as masters

• Multi-Masters (NDB, Galera)

• Multi-Masters (NDB,
Galera)
• Declare all nodes as
masters
{
"primary": {
"master": {
"master_1": {
"host": "192.168.56.44",
"port": "3306"
},
"master_2": {
"host": "192.168.56.43",
"port": "3306"
},
"master_3": {
"host": "192.168.56.42",
"port": "3306"
}
},
"slave": { },
"filters": { "random": [ ] },
"failover": {
"strategy": "loop_before_master",
"remember_failed": true
}
}
}

Galera)
{
"primary": {
"master": {
"master_1": {
"host": "192.168.56.44",
"port": "3306"
},
"master_2": {
"host": "192.168.56.43",
"port": "3306"
},
"master_3": {
"host": "192.168.56.42",
"port": "3306"
}
},
"slave": { },
"failover": {
}
}
}

Galera)
masters
• roundrobin - single node
writer (first node in
config)
{
"primary": {
"master": {
"master_1": {
"host": "192.168.56.44",
"port": "3306"
},
"master_2": {
"host": "192.168.56.43",
"port": "3306"
},
"master_3": {
"host": "192.168.56.42",
"port": "3306"
}
},
"slave": { },
"failover": {
}
}
}

Galera)
masters
config)
• random - all nodes
{
"primary": {
"master": {
"master_1": {
"host": "192.168.56.44",
"port": "3306"
},
"master_2": {
"host": "192.168.56.43",
"port": "3306"
},
"master_3": {
"host": "192.168.56.42",
"port": "3306"
}
},
"slave": { },
"failover": {
}
}
}

Galera)
masters
config)
• random - all nodes
• remember_failed is not
what it says it is
{
"primary": {
"master": {
"master_1": {
"host": "192.168.56.44",
"port": "3306"
},
"master_2": {
"host": "192.168.56.43",
"port": "3306"
},
"master_3": {
"host": "192.168.56.42",
"port": "3306"
}
},
"slave": { },
"failover": {
}
}
}

• Master-Master Demo
• https://github.com/dotmanila/demo-me/phpugph201407/
• master-master.ini
• mysqlnd_ms_mm.ini
• master-master.php

Am I Using mysqlnd? (rpm)
[revin@forge ~]$ rpm -‐q php-‐mysql.x86_64 -‐-‐requires
[…]
libmysqlclient_r.so.16()(64bit)
libmysqlclient_r.so.16(libmysqlclient_16)(64bit)
libmysqlclient.so.16()(64bit)
libmysqlclient.so.16(libmysqlclient_16)(64bit)
[…]

[revin@forge ~]$ rpm -‐q php-‐mysqlnd.x86_64 -‐-‐requires
php-‐pdo(x86-‐64) = 5.4.30-‐36.el6.art
rpmlib(VersionedDependencies) <= 3.0.3-‐1
rpmlib(FileDigests) <= 4.6.0-‐1
rpmlib(PayloadFilesHavePrefix) <= 4.0-‐1
rpmlib(CompressedFileNames) <= 3.0.4-‐1
libc.so.6()(64bit)
libc.so.6(GLIBC_2.2.5)(64bit)
libc.so.6(GLIBC_2.3.4)(64bit)
libc.so.6(GLIBC_2.4)(64bit)
libpthread.so.0()(64bit)
libpthread.so.0(GLIBC_2.2.5)(64bit)
rtld(GNU_HASH)
rpmlib(PayloadIsXz) <= 5.2-‐1
Am I Using mysqlnd? (rpm)

[revin@forge ~]$ php -‐i
[…]
!
mysql
!
MySQL Support => enabled
Active Persistent Links => 0
Active Links => 0
Client API version => 5.1.59
MYSQL_MODULE_TYPE => external
MYSQL_SOCKET => /var/lib/mysql/mysql.sock
MYSQL_INCLUDE => -‐I/usr/include/mysql
MYSQL_LIBS => -‐L/usr/lib64/mysql -‐lmysqlclient
Am I Using mysqlnd? (phpinfo)

[revin@forge ~]$ php -‐i
[…]
!
mysqlnd
!
mysqlnd => enabled
Version => mysqlnd 5.0.10 -‐ 20111026 -‐ $Id: c85105d7c6f7d70d609bb4c000257868a40840ab $
Compression => supported
SSL => supported
Command buffer size => 4096
Read buffer size => 32768
Read timeout => 31536000
Collecting statistics => Yes
Collecting memory statistics => No
Tracing => n/a
Loaded plugins => mysqlnd,example,debug_trace,
auth_plugin_mysql_native_password,
auth_plugin_mysql_clear_password
API Extensions => mysql,mysqli,pdo_mysql
Am I Using mysqlnd? (phpinfo)

Conclusion
• Yes, we can achieve HA with mysqlnd_ms
• Not for the faint of heart
• Do not rely on for HA (writes) on critical production
systems
• Good for intended use case, rw-splitting

Q&A
• http://dotmanila.com/blog/
• http://www.mysqlperformanceblog.com/
• @dotmanila
Percona is Hiring!!
http://www.percona.com/about-us/careers/open-positions

$t = true AND false; echo (int) $t;

Highly Available MySQL/PHP Applications with mysqlnd

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