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mysql jdbc connector autoReconnect=true

Июнь 16th, 2010

What makes you think jdbc autoreconnect is needed?
Application is idle for long periods at a time?
Wait_timeout too short?
Network failure or glitches?

Some good suggestions form Mark Matthews - Bug #5020

Having encountered the problem again myself today, trying to make jdbc for mysql reconnect any terminated connections using autoreconnect=true I figured out a way to work it out from the pooling side.

Introduction to the problem:

On the mysql side wait_timeout is set to default 8hrs and any connections idle for longer than that were beomg terminated despite setting the connection string to: url=jdbc:mysql://localhost:3306/dbname?autoReconnect=true. The application was thence throwing an exception.

The solution was to introduce a ping from the pooler which for “Ibatis”, the pooler technology used in this case, was:

This covers eventualities of network glitches or connections exceeding the wait_timeout having the pooler ping the database if the connection was idle for more than 10 seconds (the value is in milliseconds).

The configuration if Ibatis in this case is something like:

Ibatis


<transactionManager type="JDBC">
<dataSource type="SIMPLE">
<property value="${driver}" name="JDBC.Driver"/>
<property value="${url}" name="JDBC.ConnectionURL"/>
<property value="${username}" name="JDBC.Username"/>
<property value="${password}" name="JDBC.Password"/>
<property name="Pool.PingQuery" value="select 1"/>
<property name="Pool.PingEnabled" value="true"/>
<property name="Pool.PingConnectionsOlderThan" value="3600000"/> <!-- 1 hr -->
<property name="Pool.PingConnectionsNotUsedFor" value="10000"/> <!-- ping db 10 sec -->
</dataSource>
</transactionManager>

For every pooling technology there will be a different “Pool.PingConnectionsNotUsedFor” term, but the concept is still there. It worked like a charm.

JDBC driver=com.mysql.jdbc.Driver url=jdbc:mysql://localhost:3306/dbname username=username password=password

PS … autoreconnect is not recommended when using mysql jdbc!

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Posted in autoreconnect, connector, ibatis, jdbc, keepalive, mysql, network, networking, ping, wait_timeout

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Enabling IPv6 Support in nginx

Январь 16th, 2010

This is going to be a really short post, but for someone it could save an hour of life.

So, you’ve nothing to do and you’ve decided to play around with IPv6 or maybe you’re happened to be an administrator of a web service that needs to support IPv6 connectivity and you need to make your nginx server work nicely with this protocol.

First thing you need to do is to enable IPv6 in nginx by recompiling it with --with-ipv6 configure option and reinstalling it. If you use some pre-built package, check if your nginx already has this key enabled by running nginx -V.

The results should have --with-ipv6 option in configure arguments:

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[root@node ~]# nginx -V
nginx version: nginx/0.7.64
built by gcc 4.1.2 20080704 (Red Hat 4.1.2-46)
TLS SNI support disabled
configure arguments: --with-ipv6 ... --prefix=/opt/nginx

After you’ve got your nginx binary with IPv6 support, you need to enable it by changing listen directives in your configuration file.

If your server binds to all interfaces/IPs, you already have listen 80 or something like that in your file. Those lines should be changed to make sure you tell your nginx to bind on both IPv4 and IPv6 addresses:

1	listen [::]:80;

For situations when you do not want to listen on IPv4 interfaces, there is ipv6only=on parameter:

1	listen [::]:443 default ipv6only=on;

For configurations that need to bind to specific ip addresses you could use similar notation:

1	listen [2607:f0d0:1004:2::2]:80;

After changing your configs and testing them you need to restart (not reload) your nginx process and then check your system port bindings to make sure it works as expected:

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[root@node ~]# netstat -nlp | grep nginx
tcp 0 0 :::80 :::* LISTEN 23817/nginx
tcp 0 0 :::443 :::* LISTEN 23817/nginx

This is it, now you can add AAAA records to your main domain name or just create a dedicated ipv6.yourcompany.com sub-domain and show it to your friends