lefred

lefred

I am MySQL Community Manager for EMEA & APAC. I joined the MySQL Community Team in May 2016. I have been an OpenSource and MySQL consultant for more than 15 years. My favorite topics are High Availability and Performance.

Percona Live MySQL Conference & Expo 2013

For my first participation to THE MySQL event of the year, I have the honour of delivering a full day tutorial on Opetational DBA in a nutshell with my two Belgian colleagues (call us the be-team ;) ) and a lighting talk related to MySQL database schema migration: how to version them and manage those operations. If you don't want to miss THE essential event of the MySQL ecosystem, use code "SpeakMySQL" at checkout for 15% off! Register here: http://bit.ly/14au67Z. See you soon there !

nolinger option for Galera Load Balancer (glb)

If you test Galera synchronous replication with Percona XtraDB Cluster or MariaDB Galera Cluster you must have tried to use a load balancer like HA Proxy or Galera Load Balancer. On very heavy load, you may have issue with a large amount of TCP in TIME_WAIT like this one:
tcp        0      0 127.0.0.1:59035         127.0.0.1:3306          TIME_WAIT
This can lead to a TCP port exhaustion as explained on this post. On HA proxy since version 1.4.19, you can use the nolinger option also on TCP backends. This terminate the connection (TCP RST) as soon as the loadbalancer finished the communication. The counter part is that Aborted_clients status counter in MySQL increases with each connections' end. This counter becomes then useless. This option is not available on glb (with -l parameter) if you apply the patch attached to this post. I provide also rpm package with the patch applied :
Name        : glb
Version     : 0.9.2
Release     : 2
Architecture: x86_64
Install Date: (not installed)
Group       : Productivity/Networking/Routing
Size        : 208489
License     : GNU General Public License version 2 or later (GPL v2 or later)
Signature   : (none)
Source RPM  : glb-0.9.2-2.src.rpm
Build Date  : mer 27 fév 2013 17:15:54 CET
Build Host  : percona1
Relocations : (not relocatable)
URL         : http://www.codership.com/products/galera-load-balancer
Summary     : TCP Connection Balancer
Description :
glb is a simple user-space TCP connection balancer made with scalability and
performance in mind. It was inspired by pen, but unlike pen its functionality
is limited only to balancing generic TCP connections.

Features:
* list of backend servers is configurable in runtime.
* supports server "draining", i.e. does not allocate new connections to server,
  but does not kill existing ones, waiting for them to end gracefully.
* on Linux 2.6 and higher glb uses epoll API for ultimate performance.
* glb is multithreaded, so it can utilize multiple CPU cores. In fact even on a
  single core CPU using several threads can significantly improve performance
  when using poll()-based IO.
* connections are distributed proportionally to weights assigned to backend
  servers.
* this is a patched version providing SO_LINGER
Example:
[root@macbookair ~]# glbd -K -l --threads 6 --control 127.0.0.1:4444 127.0.0.1:3308 127.0.0.1:3306
glb v0.9.2 (epoll)
Incoming address:       127.0.0.1:3308 , control FIFO: /tmp/glbd.fifo
Control  address:        127.0.0.1:4444 
Number of threads: 6, max conn: 493, policy: 'least connected', top: NO, nodelay:
 ON, keepalive: OFF, defer accept: OFF, verbose: OFF, linger: ON, daemon: NO
Destinations: 1
   0:       127.0.0.1:3306 , w: 1.000
Router:
------------------------------------------------------
        Address       :   weight   usage    map  conns
      127.0.0.1:3306  :    1.000   0.000    N/A      0
------------------------------------------------------
Destinations: 1, total connections: 0 of 493 max

Pool: connections per thread:     0     0     0     0     0     0
If you test it please post a comment.

Percona XtraDB Cluster “bootstrap” option for init script

If you followed previous post about init script (here and here) for Percona XtraDB Cluster, I proposed a new solution to standardize the bootstrap of the cluster in debian/ubuntu and redhat/centos instead of using 2 different ways. You can read about this on launchpad bug #1152764. So now to start the first node of a cluster when no other node is already running, you just need to use bootstrap command with the init script like bellow:
# /etc/init.d/mysql bootstrap
Starting MySQL (Percona XtraDB Cluster)..... SUCCESS!
I attached the patches here too.

Percona XtraDB Cluster init script for Debian/Ubuntu patch (version 2)

Recently I wrote a blog post with a patch for Percona XtraDB Cluster Init script. But this was more a dirty hack then a real debian/ubuntu patch as Jan pointed it to me. So I rewrote that patch to not work as the init script of RedHat/CentOS but more like it should work on Debian, Now to initialize the cluster, on the very first node that will start the cluster, you need to run the following command:
root@percona1:/etc/init.d# /etc/init.d/mysql initialize
 * Starting MySQL (Percona XtraDB Cluster) database server and initialize the cluster mysqld                                  [ OK ] 
 * Checking for corrupt, not cleanly closed and upgrade needing tables.
Please note, the new command initialize. I hope this patch is better for Debian afficionados ;-)

Galera Load Balancer: new rpm for glb 0.9.2

Codership released a new version of the load balancer for Galera. I made new rpms but I forgot to share them ;) Here they are ! This new version provides ] a "single" balancing policy where all connections are directed to a single destination chosen by highest weight, a --top option that forces balancing only between the destinations with the highest weight, and a SO_KEEPALIVE option on destination connections (default: on) for timely detection of the destination failure.

As MySQL Community Manager, I am an employee of Oracle and the views expressed on this blog are my own and do not necessarily reflect the views of Oracle.

You can find articles I wrote on Oracle’s blog.