Category CentOS

innotop with support for 5.6

My colleague Kenny hit a bug with Innotop and MySQL 5.6. He submitted a bug with a patch. This is a new pre-release rpm of Innotop (1.9.0-3) that includes that patch. Enjoy it ! [UPDATE] New rpms are now available directly on Innotop's download page

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          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         :
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.

* 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
* this is a patched version providing SO_LINGER
[root@macbookair ~]# glbd -K -l --threads 6 --control
glb v0.9.2 (epoll)
Incoming address: , control FIFO: /tmp/glbd.fifo
Control  address: 
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: , w: 1.000
        Address       :   weight   usage    map  conns  :    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.

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.

CentOS 6 very slow with Vagrant

I use Vagrant to test almost everything. But since I upgraded to VirtuabBox 4.2.x and CentOS 6 as guess OS, I had the impression that everything was slower... and I get use to it... But this week-end while preparing selinux policies for Percona XtraDB Cluster, I noticed that it was really slow.... really really very very slooooow :'-( And I found the reason ! I first tried to add some kernel parameters like :
But that didn't help. Then I just enabled IO APIC on the VM's configuration and it worked much faster ! The boot of the machine was faster and in my case loading selinux policies too ! Have a look to the difference: Without IO APIC:
[root@node2 ~]# time semodule -i percona-xtradb-cluster-full.pp

real	6m3.646s
user	1m34.430s
sys	3m42.805s
[root@node2 ~]# time semodule -i percona-xtradb-cluster-full.pp

real	0m14.611s
user	0m13.829s
sys	0m0.769s
To enable IO APIC from Vagrant, these are the parameters to use in your Vagrantfile:
config.vm.customize ["modifyvm", :id, "--memory", "256", "--ioapic", "on"]

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.